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Posted on August 8, 2023October 2, 2023 by Scott Shannon

Thermocouples: Differences Between Thermocouple Types

In order to successfully execute a kiln firing schedule, it’s imperative that your kiln controller is receiving accurate temperature readings from your kiln. This is where thermocouples come into play.

Thermocouples measure temperature and send that information to the kiln controller which then automatically adjusts the power of the kiln according to its preprogrammed firing schedule.

What is a Thermocouple

A thermocouple is a self-powered temperature monitoring device that converts thermal energy into electric current in order to accurately measure the temperature of a heat source. Simple, inexpensive, reliable, durable, and capable of measuring a wide range of temperatures, thermocouples are used in a wide variety of applications. From monitoring the temperature of kilns and ovens, to residential thermostats, automotive and aircraft sensors, industrial and scientific processes, and more, thermocouples are used everywhere.

How Do Thermocouples Work?

Thermocouples consist of two different types of metal (or alloy) wires that run parallel to each other and join together at the tip. When the tip of the thermocouple (also known as the thermocouple measuring junction or the hot junction) is exposed to temperature, the two wires heat up or cool down to different temperatures, generating electromotive force. This phenomenon is known as the Seebeck Effect.

The two metal wires also connect at the reference junction (or the cold junction), which is kept at a constant, known temperature. Historically, this known temperature was created by using an ice bath for a 32° Fahrenheit reference, but today this is accomplished with electronic sensors which allow for thermocouples to be used over a range of ambient temperatures.

The voltage created corresponds with the relative temperature difference between the two junctions, allowing a sensor to calculate the temperature at the measuring junction with an accuracy of within 1° or 2° C.

Factors That Affect Accuracy

While thermocouples are reliable and widely used, there are several factors that can impact the accuracy of their readings at any given point in time:

Size: The physical dimensions of a thermocouple can affect its response time and, therefore, instantaneous accuracy. Smaller thermocouples may exhibit faster response times due to their reduced mass, but they may also be more susceptible to measurement errors caused by thermal gradients or conduction losses.
Location: The placement of a thermocouple within a kiln or oven can influence the accuracy of its readings. Factors such as proximity to heat sources, shielding from external influences, and the ability to measure representative cold junction temperatures can all impact the reliability of the measurements.
Tolerance: Thermocouples have specific tolerances, which define the maximum allowable deviation from their specified temperature-to-voltage relationship. If a thermocouple exceeds its tolerance limits, the readings may become less accurate or unreliable. It is essential to select a thermocouple with an appropriate tolerance for the desired temperature range and application.
Self-heating: The heating of a thermocouple itself can introduce errors in the temperature measurements. Self-heating occurs when the current flowing through the thermocouple generates heat, which can lead to a temperature increase at the sensing junction. This self-heating effect can result in an offset or error in the measured temperature, particularly in low-temperature applications or when high currents are used.
Kiln or Oven State: When a kiln’s elements are on, the air near the elements becomes hotter than the rest of the air inside the kiln. This temperature gradient produces convection currents which swirl warmer and colder air around inside the kiln. As this air moves and passes over the thermocouple, it can cause swings in the temperature reading depending on the response time of the thermocouple. These convection currents are less problematic when the kiln’s elements are off and the internal air temperature becomes more homogenized.
Additional Factors: Other factors that can impact thermocouple readings include electromagnetic interference (commonly produced by switching mechanical relays), oxidation or contamination of the thermocouple junctions, mechanical stress or strain on the thermocouple wires, and the type of reference junction used for cold junction compensation.

To ensure accurate temperature measurements, it is crucial to consider these factors and choose the appropriate thermocouple type, size, location, and tolerance based on the specific application requirements, as well as the type of controller you’re using. Regular calibration and maintenance of the thermocouples are also recommended to verify their accuracy and detect any drift or degradation over time. Some temperature controllers, such as TAP Kiln Controllers by SDS Industries provide diagnostics and preventative maintenance alerts based on usage to ensure thermocouple accuracy.

What are the Different Types of Thermocouples?

There are a wide variety of thermocouple types that are suitable for different types of applications. Each type of type of thermocouple has different characteristics for temperature range, sensitivity, durability, vibration resistance, chemical resistance, and application capability depending on the physical properties of its metals.

Thermocouple types are named according to a lettering system. Thermocouple Types C, E, J, N, K, and T are composed of base metals and Types B, R, S, and P are composed of noble metals. Below we’ll be exploring the characteristics and applications of the different thermocouple types.

Base Metal Thermocouples

Base metal thermocouples are the most common types of thermocouple. These thermocouples are composed of base metals or alloys, such as iron, copper, nickel, and chromel.

Type C Thermocouples

Material: Tungsten-Rhenium (+ and -)
Temperature Range: 32 – 4208° F (0 – 2320° C)
Accuracy/Limit of Errors: Standard: ± 1% or 4.5° C
Physical Properties: Type C thermocouples are capable of accurately measuring extremely high temperatures. However, they have no oxidation resistance, meaning they are only suitable for applications with vacuum, hydrogen, or inert atmospheres.
Applications: High Temperature Materials Manufacturing, Power Generation, Aerospace, Semiconductor Processing and Equipment, Military and Defense Testing

Type E Thermocouples

Material: Chromel (+) and Constantan (-)
Temperature Range: -454 – 1832° F (-270 – 1000° C)
Accuracy/Limit of Errors: Standard: ± .5% or ± 1.7° C, Special: ± .4% or ± 1° C
Physical Properties: Type E thermocouples are highly accurate with a fast response, even in sub-zero applications. They have the strongest signal and highest output of the base metal thermocouples and aren’t subject to corrosion at cryogenic temperatures (-238 – 460° F).
Applications: Gas Temperature Measurement, Cryogenics, Aerospace Industry, Applications with Magnetic Fields

Type J Thermocouples

Material: Iron (+) and Constantan (-)
Temperature Range: 32 – 1382° F (0 – 750°C)
Accuracy/Limit of Errors: Standard: ± .75% or ± 2.2° C, Special: ± .4% or ± 1.1° C
Physical Properties: Type J thermocouples are capable of accurate temperature monitoring in a vacuum or for inert materials. However, they are susceptible to oxidation at low temperatures or moist environments. While they are the least expensive general-purpose thermocouples, Type J thermocouples also have the shortest lifespan, and their accuracy will be permanently impaired if exposed to temperatures greater than 1400° F.
Applications: Plastic Manufacturing, Laboratory Processes, Ovens, Kilns, Furnaces

Type N Thermocouples

Material: Nicrosil (+) and Nisil (-)
Temperature Range: -450 – 2372° F (-270 – 1300°C)
Accuracy/Limit of Errors: Standard: ± .75% or ± 2.2° C, Special: ± .4% or ± 1.1° C
Physical Properties: Type N thermocouples have superior corrosion resistance and are capable of measuring high temperatures compared to other base metal thermocouples. However, they also have a slower response and lower sensitivity.
Applications: Refineries, Petrochemical Industry, Ovens, Kilns, Furnaces

Type K Thermocouples

Material: Chromel (+) and Alumel (-)
Temperature Range: -328 – 2282° F (-200 – 1250°C)
Accuracy/Limit of Errors: Standard: ± .75% or ± 2.2° C, Special: ± .4% or ± 1.1° C
Physical Properties: Reliable, accurate, inexpensive, with fast response across a wide rand of temperatures, Type K thermocouples are the most commonly used type of thermocouple. With oxidation resistance and radiation hardness, Type K thermocouples are extremely versatile. However, they shouldn’t be used in vacuum applications, low oxygen, or sulphuric environments.
Applications: Steel and Iron Industry, Petroleum Refineries, Nuclear Applications, Chemical Production, Ovens, Kilns, Furnaces

Type T Thermocouples

Material: Copper (+) and Constantan (-)
Temperature Range: -328 – 662° F (-250 – 350° C)
Accuracy/Limit of Errors: Standard: ± .75% or ± 1° C, Special: ± .4% or ± .5° C
Physical Properties: Type T thermocouples are extremely stable and capable of operating at extremely cold temperatures. However, it has a narrow temperature range compared to other thermocouple types.
Applications: Food Production, Cryogenics, Deep Freezing, Laboratory Processes

Noble Metal Thermocouples

Noble metal thermocouples use platinum alloys, making them accurate at extremely high temperatures – but also significantly more expensive!

Type B Thermocouples

Material: Platinum-Rhodium (+ and -)
Temperature Range: 32 – 3092°F (0 – 1700° C)
Accuracy/Limit of Errors: Standard: ± 5% or ± .5° C
Physical Properties: Type B thermocouples are extremely accurate and stable at extremely high temperatures. They are corrosion-resistant and are suitable for oxidizing environments. However, they are susceptible to contamination and require appropriate protection.
Applications: Industrial Glass, Metal Melting and Pouring, Analytical Instrument Calibration, Nuclear Reactor Temperature Regulation, Semiconductor Processing and Equipment

Type R Thermocouples

Material: Platinum-Rhodium (+) and Platinum (-)
Temperature Range: 32 – 2642°F (0 – 1450° C)
Accuracy/Limit of Errors: Standard: ± .25% or ± 1.5° C, Special: ± .1% or ± .6° C
Physical Properties: With a higher percentage of rhodium, Type R thermocouples are more expensive than other noble metal thermocouple types, but also have a higher output and improved stability. They are resistant to oxidation as well as chemically aggressive material. However, they are susceptible to contamination and require appropriate protection.
Applications: Industrial Glass, Power Generation, Mining, Laboratory Processes, Temperature Sensors, Ovens, Kilns, Furnaces

Type S Thermocouples

Material: Platinum-Rhodium (+) and Platinum (-)
Temperature Range: 32 – 2642°F (0 – 1450° C)
Accuracy/Limit of Errors: Standard: ± .25% or ± 1.5° C, Special: ± .1% or ± .6° C
Physical Properties: Type S thermocouples are extremely similar to Type R thermocouples in regard to physical properties. However, a slightly lower percentage of rhodium makes Type S thermocouples slightly less stable.
Applications: Industrial Glass, Power Generation, Mining, Laboratory Processes, Temperature Sensors, Ovens, Kilns, Furnaces

Type P Thermocouples (Platinel II)

Material: Palladium-Platinum-Gold (+) and Gold-Palladium (-)
Temperature Range: 32 – 2543°F (0 – 1395° C)
Accuracy/Limit of Errors: Standard: ± .2mV (up to 1200° C)
Physical Properties: Type P thermocouples are designed to approximate the same curve as Type K thermocouples. They are extremely accurate and stable. Type P oxidation-resistant and can be used in inert atmospheres, but they are susceptible to contamination and require appropriate protection.
Applications: Regulating Gas Turbine Engines, Temperature Sensors, Ovens, Kilns, Furnaces

What Thermocouple Type Should I Use for my Kiln or Heat Treat Oven?

The type of thermocouple you should use for your kiln or heat treat oven largely depends on the temperature requirements of your firing schedules. Due to its durability, reliability, and accuracy across an extensive range, a Type K thermocouple is a popular choice for most kilns and heat treat ovens. Type K thermocouples are suitable for most heat treat applications.

However, some materials, such as porcelain, have temperature requirements that exceed the range for Type K thermocouples, in which case you may consider using a Type R or Type S thermocouple. The original TAP Kiln Controller by SDS Industries supports Type K, Type R, and Type S thermocouples. The TAP II, along with every other TAP Product by SDS industries, supports Type K thermocouples.

Pair Your Thermocouple with the Right Temperature Controller

The TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use temperature controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven to allow you to easily manage and execute your kiln firing schedules.

We invite you to explore our selection of digital kiln controllers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP-Controlled Kilns and Heat Treat Ovens through one of the following distributors:

Posted on August 1, 2023August 8, 2023 by Brittany Gabel

Kiln Firing Chart for Pottery and Ceramics [Infographic]

When it comes to firing ceramics, different types of clays and glazes are rated for different temperatures. A kiln firing chart, also known as a cone firing chart, is a useful tool for understanding the effects of temperature on different types of clays and glazes, as well as determining what firing schedule setpoints should be used depending on the cone rating of the media you’re firing.

What Temperature Is Pottery Fired At? Understanding Different Types of Ceramics

What temperature is pottery fired at? Well, that depends. There a three main types of clay that are used to make pottery: earthenware, stoneware, and porcelain. Each of these has different temperature requirements, as well as different properties once fired.

1. Earthenware

Earthenware clay is the most common type of clay used in ceramic firing today. Earthenware is softer than the other types of clay, making it easier to work with and more forgiving. Earthenware also has the lowest firing temperature requirements, which is why it was the first type of clay used to make pottery during the early stages of kiln history.

A collection of fired earthenware pottery to demonstrate the qualities of fired earthenware — **Fired earthenware is porous and relatively soft. Earthenware ranges from white and gray hues to browns, oranges, and reds.**

Firing Temperature

Earthenware clay typically reaches maturity (or optimum hardness) between 1745° F and 2012° F, although some low-firing earthenware clays can be fired in temperatures as low as 1200° F.

Cone Rating

Earthenware is what’s known as a “low fire” clay. Earthenware clay can be fired from Cone 015 up to Cone 1, but Cone 04 is the average.

Physical Properties

Since earthenware is fired at lower temperatures, it typically remains porous, relatively soft (you can scratch it with a knife!), and still absorbs water. Glazes are often required to make earthenware harder and watertight.

2. Stoneware

Stoneware is a “mid-range” or “high fire” clay that requires higher firing temperatures and a longer firing schedule than earthenware. Once it has been fired, stoneware is hard, dense, and rocklike – hence the name!

A collection of fired stoneware ceramics, demonstrating its hard, rocklike texture — **Named for its hard, rock-like texture, fired stoneware is often gray or brown.**

Firing Temperature

Stoneware reaches maturity between 2000° F and 2400° F – hotter than lava!

Cone Rating

Stoneware is typically fired between Cone 2 all the way up to Cone 12, with Cones 7 and 10 being the most common for mid-range stoneware and high fire stoneware, respectively.

Physical Properties

Since stoneware is fired at higher temperatures, it has time to fully vitrify, or form a glassy, nonporous bond on its surface. Finished stoneware is durable, hard, and nonporous. Unlike earthenware, stoneware is waterproof once fired even without the use of glazes.

3. Porcelain

Originating in China in 1600 BC, porcelain is a “high fire” clay that produces extremely hard, shiny, often white or translucent ceramics. Also known as kaolin clay (named after Kao-ling hill in China, where it was mined for centuries), raw porcelain is extremely dense and difficult to work. Often, porcelain is mixed with other types of clay to improve its workability.

A collection of fired porcelain ceramics, demonstrating its hard, glasslike white exterior — **Fired porcelain is hard, smooth, and glasslike – notable for its white or translucent color**

Firing Temperature

Porcelain typically reaches maturity between 2381° F and 2455° F – however, pure kaolin reaches maturity at 3272° F!

Cone Rating

Porcelain clay is fired between Cone 10 and Cone 13.

Physical Properties

Once fired, porcelain is extremely hard and fully vitrified, making it watertight and non-absorbent. Porcelain is noted for its distinct white color.

Understanding Firing Cone Ratings

As we mentioned earlier, different ceramic materials and glazes have a cone rating. Firing cones, or pyrometric cones, are a simple pyrometric device that indicate kiln temperature. Firing cones melt when exposed to a certain temperature for a prolonged period of time. Different ceramics and glazes are given a cone rating to indicate the temperatures at which they’ll reach maturity.

Firing cones range from 022 to 14, with 022 being the lowest temperature and 14 being the highest. As you’ll see on the kiln firing chart below, when a firing cone rating has a ‘0’ in front of it, a lower number indicates a higher fire temperature.

However, for firing cones without a ‘0’ in front of their rating, higher numbers indicate higher firing temperatures.

Kiln Firing Chart [Infographic]

In the kiln firing chart below, you’ll be able to see which temperatures correspond with various cone ratings and materials. The color gradient indicates the incandescence of the kiln at various temperatures, and the column to right indicates how the physical properties of ceramic changes at each temperature.

Download PDF!

Reach the Right Setpoints on Your Kiln Firing Chart with Ease and Precision

The TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use pottery kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven to allow you to easily manage and execute your kiln firing schedules.

We invite you to explore our selection of digital kiln controller, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP-Controlled Kilns and Heat Treat Ovens through one of the following distributors:

Posted on July 25, 2023October 24, 2023 by Brittany Gabel

Understanding Kiln Firing Schedules for Glass, Ceramics, Pottery, and Heat Treat

The primary function of a kiln controller is to help users input (and successfully execute!) their kiln firing schedules…but what is a kiln firing schedule? Below, we’ll be helping you understand kiln firing schedules, as well as how firing schedules differ for materials such as glass, ceramic, pottery, and metal heat treat!

Definition of Kiln Firing Schedules

A kiln firing schedule is a progression of steps, made up of temperature changes over specific time intervals, that a kiln moves through during a firing. Each step of a kiln firing schedule is made up of four components:

Step #: Also known as a ‘segment,’ step # represents the order in which the steps of the schedule occur.
Ramp Rate: Measured in degrees per hour, the ramp rate is the speed at which the kiln is heated up or cooled down.
Setpoint: Measured in degrees, the setpoint is the desired temperature the kiln reaches during each step.
Hold Time: Also, known as a ‘soak,’ hold time is the length of time (defined in days, hours, or minutes) the kiln stays at a specific setpoint before advancing.

Each of these components determines the properties of the finished ware once the firing schedule reaches completion. Even extremely minor variances in adhering to kiln firing schedules can have a major impact on the finished result, so it’s important to accurately input firing schedules into your kiln controller and to utilize kiln controllers that are able to automatically execute kiln firing schedules with extreme precision.

Example of a Kiln Firing Schedule

Kiln firing schedules, sometimes colloquially referred to as programs or firing schedules, can best be described as the road map the controller uses to execute a firing. While kiln firing schedules can string together as many steps as necessary to achieve the desired firing result, below we’ll be looking at an example of a three-step firing schedule:

Assuming the kiln starts at room temperature, or 70° F, the example schedule shown above will result in a firing that takes 5 hours and 24 minutes to complete. Below is a visual graph representing the firing profile of this schedule:

In this graph, we can see that the kiln follows a 500 degree-per-hour ramp rate from time 0 (when the kiln was started) to 950 degrees (the first setpoint). Once the setpoint is achieved, the controller regulates the temperature to keep the kiln at 950° for 30 minutes.

Once the hold time from the first step is completed, the kiln advances at a rate of 1200 degrees-per-hour to a setpoint of 1425° and holds there for 20 minutes.

Finally, the kiln moves to step three, cooling at a rate of 300 degrees-per-hour down to a setpoint of 700°. Because the hold time at Step #3 is zero, the kiln firing schedule is now complete!

See our article on Alerts and Alarms so you can be notified when your kiln firing schedule reaches certain firing points! 

Ramp/Hold vs Time-to Temp Schedules

Kiln firing schedules can also be expressed in different formats. The example above is the common Ramp/Hold format, which can also be described as a Ramp/Soak or Ramp/Dwell schedule. This is the most common kiln firing schedule format, and it is also the format that is supported by TAP Kiln Controllers.

However, kiln firing schedules can also be written in a Time-to-Temp format, which contains all of the same information but prioritizes the timing of the firing as opposed to the temperature of the firing.

When generating a Time-to-Temp schedule, you are, in effect, saying “I want to be at 950 degrees in 1 hour and 45 minutes.” At that point, the controller is responsible for converting the defined “Time-to-Temp” into a usable Ramp Rate. By saying we want to be at 950° in 1 hour and 45 minutes, and assuming we’re starting from 70°, we’ve essentially created a firing schedule with an implied ramp rate of 500 degrees-per-hour.

NOTE: Some controllers that use Time-to-Temp format do not report accurate ramp rate, which can affect outcomes of the firing schedule. For instance, a Time-to-Temp controller might report that your kiln went from 100° to 1250° in one minute, because that was what it was programmed to do, even though achieving that level of temperature change over that time interval simply isn’t possible.

Below is the exact same kiln firing schedule from before written in a Time-to-Temp format:

The firing graph for both formats would look exactly the same – and executing either format would yield the same outcome once the firing schedule reaches completion (assuming the controller was capable of converting the Time-to-Temp into an accurate ramp rate). The only difference is how the kiln firing schedule is expressed. What was defined in three steps in the Ramp/Hold format requires five steps in the Time-to-Temp format, despite yielding the same firing profile.

What Factors Does a Kiln Firing Schedule Depend On?

Kiln firing schedules are dependent on the material/media being fired, as well as the physical capabilities of the kiln. There is no one-size-fits-all approach to kiln firing schedules, as the material within the kiln will require its own unique schedule to achieve optimal results. Later in the article, we’ll be looking at examples of firing schedules for glasswork, firing ceramics, and metal heat treat.

Limitations of Kiln Firing Schedules

Now that you know the components of a kiln firing schedule, you should also understand the limitations. The physical capabilities of the kiln dictate certain physical boundaries that cannot be overcome. The material of the kiln, chamber size, power rating, and thermocouple gauge all contribute to the kiln’s demonstrated performance.

As kilns approach higher temperatures, their ability to heat at defined ramp rates begins to fall off. A kiln that can heat at a ramp rate of 3600 degrees-per-hour while at 200° will likely be unable to generate the same ramp rate at 1500°. This is a result of the kiln material and power rating.

Thermocouples are used to read the temperature inside a kiln chamber and communicate that temperature to the kiln controller. A kiln with an 8-gauge thermocouple will respond much slower to temperature input than a 20-gauge thermocouple. This can result in overshoot at low setpoints as the thermocouple needs time to “catch-up” to the heat that has been applied to the kiln.

Kiln Firing Schedules for Glass

While the kiln firing schedule example above was hypothetical, in this section we’ll explore actual kiln firing schedules for different types of glasswork techniques.

Please Note: Each of these schedules is for 90 COE glass. Additionally, each firing schedule will have to be adjusted according to your specific kiln, the size of your project, as well as the type of glass you’re using – some experimentation will be required, so please just use these as a general guideline.
For additional in-depth technical information about using your kiln to fire glass, please visit https://www.bullseyeglass.com/index-of-articles/.

Full Fuse Firing Schedule

A full fuse is when you use heat and time to combine two or more layers of glass to form one single solid piece of glass. The layers of glass fuse together – hence the name! Below is a full fuse firing schedule for projects that are smaller than 12”.

400°F/Hr to 1250°F – hold 30 minutes.
600°F/Hr to 1490°F – hold 10 minutes.
AFAP°F/Hr to 900°F – hold 30 minutes.
150°F/Hr to 700°F – hold 0 minutes.
AFAP°F/Hr to 70°F – hold 0 minutes.

You can find temperature guidelines for additional glasswork processes here.

Glass Casting Firing Schedule

Glass casting is when you melt glass until it is soft and malleable enough to conform to a mold. The glass then hardens to create a glass object in the shape of the mold. Below is a glass casting firing schedule for a small open face mold cast:

100°F/Hr to 200°F – hold 6 hours.
100°F/Hr to 1250°F – hold 2 hours.
600°F/Hr to 1525°F – hold 3 hours.
AFAP °F/Hr to 1200°F – hold 4 hours.
50°F/Hr to 900°F – hold 6 hours.
12°F/Hr to 800°F – hold 1 minute.
20°F/Hr to 700°F – hold 1 minute.
72°F/Hr to 70°F – hold 1 minute.

Additional details about casting firing schedules can be found here.

Annealing Firing Schedule

Annealing glass is the process of stabilizing glass during the cooling process by holding it at a steady temperature to give it time to strengthen. COE 96 glass is typically annealed at a setpoint of 960°F. However, the size of the glass, its thickness, as well as the number of layers being used determines how long the anneal hold needs to be.

From the example of the Full Fuse Firing Schedule above, we highlighted the steps that involved annealing in green:

Notice that Step #3 has the kiln hold at the annealing setpoint 900°F for 30 minutes in order to give the fuse time to stabilize, and then Step #4 and Step #5 have the kiln slowly cooling down from the setpoint to the final temperature.

See our article Benefits of Using a Digital Controller for Glass Kilns for more information about using your kiln for glasswork!

Kiln Firing Schedules for Ceramics

Before getting into kiln firing schedules for ceramics, it’s important to know what Cone # the material you’re firing is rated for. This represents the setpoint at which the type of material you’re using is properly fired. So, for example, Cone 04 clay would need to reach a setpoint of at least 1945°F whereas Cone 6 Porcelain would need to reach a setpoint of 2232°F.

Please Note: All of these kiln firing schedules are for 04 Cone clay. Just like with glasswork, each firing schedule will have to be adjusted according to your specific kiln, the size of your project, as well as the type of clay, stoneware, or porcelain you’re using – some experimentation will be required, so please use these as a general guideline.

Candling Firing Schedule

Candling is the process of allowing clay to fully dry prior to high temperature ceramic firings. This involves heating your kilns to a low temperature for a prolonged period of time. Below is an example of a kiln firing schedule for candling your clay:

150°F/Hr to 150°F – hold 12 hours.

Simple, right? However, this is just to get the clay ‘bone-dry’ before firing it, since the natural moisture of the clay, if fired too quickly, can cause your project to crack and fissure!

Bisque Firing Schedule for Cone 04 Ceramics

A bisque firing is the process of turning clay into ceramics! Below is a slow bisque firing schedule for Cone 04 clay:

80°F/Hr to 250°F.
200°F/Hr to 1000°F.
100°F/Hr to 1100°F.
180°F/Hr to 1695°F.
80°F/Hr to 1945°F.

You’ll notice that this firing schedule doesn’t include any hold times. However, the total firing time is 13 hours and 26 minutes. So how does that work? In this case, the firing time is dictated by the ramp rate – or the amount of time it takes for your kiln to reach each setpoint in the firing schedule.

Glaze Firing Schedule for Cone 04 Ceramic

When firing pottery, it’s important to match the Cone # of your glaze to the Cone # of your clay. In this case, we’re using Cone 04 clay, which is a “low-fire” clay. Therefore, we’d want to use a glaze that’s in the Cone 06-04 range. In other words, the temperature of the glaze firing schedule shouldn’t exceed the temperature of the bisque firing schedule.

150°F/Hr to 250°F.
400°F/Hr to 1695°F.
100°F/Hr to 1945°F.

See our article on How to Use a Pottery Kiln Temperature Controller for more information on how to fire ceramics!

Firing Schedules for Heat Treating Metals

Just like with glasswork and pottery, kiln firing schedules for metal heat treat is extremely dependent on the type of material you’re using. But, additionally, it’s dependent on the qualities you want the finished metal to have. For heat treat, the rate at which you cool the metal has a significant impact on the molecular structure of the metal. For these examples, we’ll be working with 1095 steel.

Please Note: All of these kiln firing schedules are for 1095 steel. Just like with Each firing schedule will have to be adjusted according to your specific kiln or heat treat oven, the type of metal you’re using, its thickness, as well as the desired properties – some experimentation will be required, so please just use these as a general guideline.
You can find more information about setpoints and cooling rates for different effects on different types of metal here.

Normalizing Firing Schedule for 1095 Steel

Normalizing is a process where metal is heated to an extremely high temperature for a defined period of time and then either air-cooled or furnace cooled at a controlled ramp rate. Normalizing relieves internal stress and ensures uniformity, resulting in harder, stronger metals. Below is a normalizing firing schedule for 1095 steel:

AFAP°F/Hr to 1600°F – hold for 15 minutes.
Remove knife or blade from the oven and allow to air-cool.

Quench Hardening Firing Schedule for 1095 Steel

Quenching is the process where metal is heated and then cooled rapidly by dipping it into an oil, polymer, or water, resulting in very hard, very brittle metal. This increases the hardening of the metal (but also its brittleness). Below is a quench firing schedule for 1095 steel:

AFAP°F/Hr to 1600°F – hold for 15 minutes.
Remove knife or blade from the oven and quench in fast oil to 150°F.

Tempering Firing Schedule for 1095 Steel

After hardening, the metal is heated to a lower temperature to reduce excessive hardness and relieve internal stress. Tempering makes metals less brittle – it should be done within two hours after the steel cools from the quench hardening process. Below is a tempering firing schedule for 1095 steel:

AFAP°F/Hr to 400°F – hold for 2 hours.
Allow knife or blade to slowly cool – either air-cooled or within the oven.

You’ll notice that most heat treat applications have simple kiln firing schedules that only involve a single setpoint and aren’t dependent on ramp rate. For this reason, it might make sense to use a single setpoint controller for heat treat applications like the TAP & Go by SDS Industries.

Check out Guide to Choosing Heat Treating Controllers for more information about different types of heat treatments!

The Easiest Way to Precisely Execute Kiln Firing Schedules

The TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use digital kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven to allow you to easily manage and execute your kiln firing schedules.

We invite you to explore our selection of programmable kiln controllers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP-Controlled Kilns and Heat Treat Ovens through one of the following distributors:

CTA: A Better Way to Manage and Execute Your Kiln Firing Schedules

Posted on July 11, 2023July 11, 2023 by Brittany Gabel

14 Types of Electric Kiln Temperature Controllers

When it comes to controlling the temperature of an electric kiln, there’s a wide variety of electric kiln temperature controller options. Below are 14 types of kiln temperature controllers – from old school analog kiln sitters to advanced digital kiln controllers for complex firing processes.

Types of Electric Kiln Temperature Controllers

1. Manual Kiln Temperature Controllers

When kilns became electric in the early 20th century, every electric kiln had manual controls. With manual kiln temperature controllers, users set the temperature of their kiln through a combination of analog dials and switches. However, manual kiln controllers cannot adjust the temperature of the kiln or advance through a firing schedule without direct user input.

This means that manual kiln temperature controllers require constant hands-on management and aren’t suited for executing complex firing schedules that require high degrees of precision. However, since they’re inexpensive and have a minimal learning curve for managing user inputs (using a manual kiln controller is a lot like using a kitchen oven), manual kiln controllers are still widely used today.

2. Kiln Sitters

The first major innovation to electric kiln temperature controllers was the invention of the kiln sitter in the 1950s. Used with manual kiln temperature controllers, the kiln sitter was the original limit controller. Limit controllers add kiln safety by ensuring a kiln shuts off when a certain temperature threshold is met. Kiln sitters accomplish this for manual kilns through primitive technology. A sitter cone, inserted in the kiln sitter, melts at a certain temperature causing the kiln to power off.

Illustration showing the components of a kiln sitter with labels. — **Although outdated compared to the automatic kiln controllers of today, the invention of the kiln sitter was a major early innovation in electric kiln temperature controllers.**

3. Automatic or Digital Kiln Temperature Controllers

In the mid-1980s, the automatic kiln controller was invented. Automatic kiln controllers significantly streamline the firing process by managing the temperature of an electric kiln without user input. Also known as digital controllers, automatic kiln controllers allow users to program their device to reach the right temperatures at the right times without their direct oversight.

Automatic kiln controllers are far more precise than manual kiln controllers and leave less room for user error, making them more suitable for more complex firing schedules like those used for glasswork or some types of ceramic firings.

The first automatic kiln temperature controllers used analog inputs and had extremely complicated menus and user interfaces! However, over the last several decades automatic kiln temperature controllers have evolved massively. Today’s most advanced automatic kiln controllers are extremely easy to use and include responsive touchscreen controls, an intuitive UI, full control and extensive diagnostics, real-time monitoring and data, Wi-Fi connectivity, and mobile app integration.

**The TAP Kiln Controller is the most advanced automatic electric kiln temperature controller on the market today.**

4. 3-Key Kiln Temperature Controllers

For early automatic kiln controllers, users had analog buttons (or keys) to navigate menus and set the temperature of their electric kilns. A 3-key kiln temperature controller has three keys which the operator uses to program the kiln. As you can imagine, this can get extremely complicated! However, 3-key kiln controllers are still sold by certain manufacturers.

5. 12-Key Kiln Temperature Controllers

A 12-key kiln temperature controller includes additional keys, which makes programming an electric kiln slightly more convenient. However, compared to other more advanced electric kiln temperature controllers, 12-key controllers are still complicated to use and don’t present the best user experience.

(Note: If you’re still using a 3-key or 12-key controller, conversion kits allow you to easily replace them with more advanced digital touchscreen kiln controllers.)

6. Touchscreen Kiln Temperature Controllers

In 2015, SDS Industries released the TAP Kiln Controller which was the first commercially available electric kiln temperature controller to use a touchscreen user interface. Touchscreen kiln controllers make programming and monitoring temperature for an electric kiln much more intuitive and user friendly than 3-key and 12-key controllers.

With touchscreen kiln temperature controllers, navigating menus and creating firing schedules can be accomplished with just a few finger presses, and a larger screen and graphical UI allows users to see more details about their firing schedule and view detailed firing charts and diagnostics.

7. Multi-zone Kiln Temperature Controllers

Electric kilns come in two general configurations: single-zone and multi-zone kilns. Electric kilns are heated by resistive metal elements, much like those seen in a toaster oven. For single-zone kilns, all of the kiln’s elements respond to input from a single thermocouple. For multi-zone kilns, multiple thermocouples are used to sense temperature in different sections of the kiln and adjust power to the elements accordingly.

Multi-zone electric kiln temperature controllers, such as the TAP Kiln Controller, include multiple thermocouple inputs to set specific temperatures for different sections of the kiln, allowing users to obtain consistent firing results in a single large kiln.

8. Single-zone Kiln Temperature Controllers

Single-zone electric kiln temperature controllers, on the other hand, only have a single thermocouple, which is used to control all of the elements of a kiln and achieve a single temperature. Currently, the TAP II Kiln Controller is the most advanced and easy-to-use temperature controller for single-zone electric kilns and ovens on the market today.

**The TAP II Controller is an advanced single-zone kiln temperature controller, with an intuitive, graphical UI, built-in Wi-Fi, and integration with the TAP Kiln Control Mobile App.**

9. Internet Kiln Controllers

Internet kiln controllers, or Wi-Fi kiln controllers, utilize a Wi-Fi signal to allow users to control and monitor their kiln from their mobile device or tablet. Internet kiln controllers give users far more flexibility and freedom when it comes to operating their electric kilns, allowing them to remotely create, modify, and execute firing schedules, monitor their kiln with real-time updates and push notifications, and skip steps and abort firings.

All of the TAP Kiln Controllers by SDS Industries have Wi-Fi capability and pair with the TAP Kiln Control Mobile App to give users almost complete remote control of their electric kiln.

The TAP Micro is an internet kiln controller that users control entirely from their smartphone or tablet. — **The TAP Micro, now available for pre-order, is an internet kiln controller that users control entirely from their smartphone or tablet!**

10. Single Setpoint Kiln Temperature Controllers

Single setpoint kiln controllers are a simplified electric kiln temperature controller option that allows users to program their kiln to reach a single setpoint (or temperature) for an indefinite hold. Not all firing schedules require multiple setpoints or specific ramp rates (the speed at which a kiln heats up). Single setpoint electric kiln temperature controllers are ideal for users who are making blades, knives, or doing other heat treat processes, or for glassblowers and flameworkers who are using pick up ovens.

11. Limit Controllers

Limit controllers, also known as high limit controllers or safety limiters, are redundant temperature monitoring devices that allow users to pre-program their electric kiln to automatically shut off if the kiln exceeds a specified temperature. While limit controllers usually aren’t suited to be the primary control method on an electric kiln, they are an important part of kiln safety and can protect you, your equipment, and your property in the case of relay or system failure.

The TAP Monitor is the most advanced limit controller and digital pyrometer, allowing users to add precise, remote, real-time digital temperature readings and redundant safety shut-off to any kiln or oven. — The TAP Monitor, now available for pre-order, is the most advanced limit controller and digital pyrometer, allowing users to add precise, remote, real-time digital temperature readings and redundant safety shut-off to any kiln or oven.

12. Process Controllers

A process controller is an automatic electric kiln temperature controller that employs a closed-loop digital feedback system to control and regulate the temperature of industrial control applications more precisely. Process controllers use a mathematical formula to calculate the difference between the input temperature and the current temperature of the application. The process controller then adjusts the output to compensate for the detected changes in the system, ensuring that the current temperature is as close to the expected temperature as possible.

TAP Kiln Controllers utilize PID (“Proportional Integral Derivative”) control algorithms to ensure precise schedule following with the fastest response with minimal overshoot and limited steady-state error.

13. ICS Kiln Controllers

ICS stands for Industrial Control System. An ICS kiln controller is a type of process controller that is rated for industrial applications. Industrial kilns are large and high-powered and require extremely high degrees of precision and consistency, usually accomplished by a control algorithm.

14. Standalone Automatic Kiln Controllers

How do you convert a manual electric kiln to automatic controls? A standalone automatic kiln controller is a plug-and-play solution to upgrade a manual kiln to digital controls. All you have to do is run the thermocouple attached to the standalone kiln controller to the interior of your kiln and plug your electric kiln into the standalone unit. This enables a standalone automatic kiln controller to bypass your manual control system, enabling you to enjoy all the benefits of an advanced digital touchscreen controller.

A table top standalone kiln controller allows you to easily upgrade a manual kiln to digital controls. — **TAP Standalone Automatic Kiln Controllers allow users to easily upgrade their manual kiln to automatic controls.**

Enjoy the Most Advanced, User-Friendly Electric Kiln Temperature Controllers

The TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use electric kiln temperature controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Control Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

We invite you to explore our selection of electric kiln temperature controllers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP-Controlled Kilns and Heat Treat Ovens through one of the following distributors:

Posted on July 3, 2023August 3, 2023 by Scott Shannon

A Complete History of Kilns

For millennia, humans have been using kilns to fire pottery, ceramic, glass, brick, limestone, grain, metal objects, and other materials. It’s not hyperbole to say that the history of kilns is the history of civilization. Dating back to the rise of agriculture in the Neolithic Age, humans have been using kilns to create the objects they need to support their community – from baking breads and cereals, to creating containers for grain and waters, crafting blades, knives, and tools, and creating fertilizer, mortar, art, and ornamental objects.

Throughout the past 10,000 years, the kiln has undergone many iterations and advancements, resulting in the modern industrial and at home kilns we use today. Today, we’ll be looking at the rich history of kilns from around the globe!

The Early History of the Kilns: 8000 – 6000 BC

The first kilns date back to approximately 8000 BC. Originating in the Near East, early kilns were pit fire kilns – consisting of holes or trenches dug into the earth where wares were placed and then surrounded and covered by wood or other combustible material. While this design was thermally inefficient, unstable, and unpredictable, the insulation from the earth allowed pottery to reach high enough temperatures to fire at least some of the time.

These early pit fire kilns were often temporary structures – and we only know they existed based on the remains of pit fired pottery dating back to this time period. However, the earliest kilns were prone to failed firings and fired pottery was often brittle.

A pit fire kiln. — ***The pit fire kiln was the earliest iteration of the kiln.***

The First Known Kiln: 6000 BC

The earliest known surviving kiln dates back to 6000 BC at the Yarim Tepe site in modern day Iraq. This kiln, which still utilized an earthen firing chamber, represented a major advancement in kiln technology. The kiln was double-chambered, with a clay grate placed over the firing chamber for stacking wares – and its remaining walls suggest that it was dome-shaped at the top to create an updraft and prevent thermal loss (a design also known as a beehive kiln).

In other parts of Mesopotamia, the design of chambered kilns continued to evolve over the next few millennia to be more thermodynamically efficient, allowing for greater volumes of pottery to be fired at higher temperatures.

Early Advancements in Kiln Technology: 3000 – 300 BC

By approximately 3000 – 2500 BC, the ancient Egyptians had begun using vented chambers that allowed wares to be fired while keeping them completely separate from the fuel source. These kilns were built vertically, with an open fire at the bottom that could be stoked to regulate temperature. This design allowed the fire to receive more oxygen while still remaining controlled and thermodynamically efficient.

By the 18th Dynasty (1550 – 1292 BC), the Egyptians had begun firing glazes for pottery and creating early glasswork to imitate precious stones such as turquoise.

An example of ancient Egyptian ceramic glaze. — **Ancient Egyptians pioneered the use of glasswork and ceramic glazes.**

The ancient Greeks (3000 BC – 300 BC) expanded on the design of Mesopotamian kilns, primarily favoring beehive constructions. Greek kilns were built partially into the earth, with an underground firing chamber. They used clay, and later brick, to construct additional chambers for piling vases and smoke collection.

Ancient Grecian pottery. — **Examples of ancient Grecian pottery.**

The Rise of Industrial Kilns: 1600 BC – 500 AD

The Romans (625 BC – 476 AD) refined Greek kiln design, adding air flow piping to keep smoke from coloring the fired products, as well as chimneys to improve draft. Improved building materials such as brick and concrete allowed the Romans to build large-scale industrial kilns that were capable of firing up to 40,000 ceramic vessels at a time! The Romans used these industrial kilns to create the clay tile they used throughout their empire.

The remains of an ancient Roman industrial kiln in Morgantina. — **The remnants of an ancient Roman industrial kiln in Morgantina, Italy.**

The Romans are also attributed with the creation of lime kilns, which they introduced to Britain. Burning limestone was used to create mortar and concrete, allowing for the creation of the famous structures of the Roman Empire. (Later, this technology was used for construction during the Middle Ages – and then to create fertilizer during the 18th century).

In Great Britain, early examples of climbing kilns have been found from during the time of Roman occupation. Climbing kilns (or tunnel kilns) were long, multichambered kilns built into hillsides. A fire would be lit at the bottom and, since heat rises, the temperature of the kiln would increase with greater regularity, allowing for greater quantities of pottery to be fired.

Meanwhile, across the world, the Chinese had already perfected the art of climbing kilns. “Dragon kilns” as they were known in China, first began appearing during the Shang Dynasty (1600 – 1046 BC). By the Common Era, “dragon kilns” were widespread throughout China, sometimes reaching up to 60 meters long and capable of consecutively firing 25,000 pieces. Chinese “dragon kilns” were extremely well designed and capable of reaching up to 1400° C in order to fire stoneware and porcelain.

An example of ancient Chinese porcelain (c. 14th- 11th centuries BC) — **By c. 1400 – 1100 BC, ancient Chinese kiln technology was advanced enough to fire porcelain.**

An Increase in Efficiency and New Techniques: 400 AD – 1700 AD

The Japanese further refined Chinese kiln construction beginning in the 5th Century, creating the famous Anagama and Noborigama kilns. Over the next millennium, Japanese kilns evolved to become extremely thermodynamically efficient. This efficiency allowed the Japanese to later craft the ornate, sophisticated porcelain pieces the country became famous for – the lineage of using traditional techniques in Japan for firing porcelain and ceramics is still alive today!

**A climbing kiln in Kyushu Island, Japan.**

In Europe, throughout the Medieval and Renaissance periods, kilns continued to be an important part of day-to-day life. By the Renaissance, potters had begun using muffle kilns (or reduction kilns) for second or third firings, allowing for the application of additional glazes and majolica. These additional firings allowed for the creation of lusterware, which has iridescent metal glazes and was highly valued during that time period. (However, it’s worth noting that this technique had already been discovered almost 800 years earlier – with lusterware first appearing in modern day Iraq in the early 9th century).

Kilns During the Industrial Revolution: 1700 AD – 1900 AD

As with many industries and manufacturing processes, the Industrial Revolution had a major impact on kiln design. Coal (or anthracite) replaced wood burning and charcoal as the primary fuel source for kilns and ovens. In England, bottle kilns, famous for their bottle-shaped flutes, became commonplace. Despite their inefficiency, bottle kilns were widely used into the mid-20th century.

Bottle kilns in Stoke-on-Trent, England — *Named for their distinctive bottle-like shape, bottle kilns were widely used for industrial processes in England during the late 18th and 19th centuries.*

During this time period, industrial kilns grew in scale – with large factories capable of mass-producing ceramics and other fired goods.

The Rise of the Modern Kilns: 1900 AD – Present

During the Industrial Age, coal-burning kilns were slowly phased out for gas kilns and electric kilns – and the modern kiln was born! Compared to prior kilns, gas kilns and electric kilns were extremely efficient and capable of reaching high temperatures. These new fuel sources and advancements in technology allowed kilns to become extremely big and extremely small – from industrial kilns that are hundreds of yards long to hobby kilns that are about the size of a toaster oven!

Although early modern kilns were all manually controlled, the use of gas and electricity allowed for far more control and precision in regulating kiln temperature, which allowed for more complex firing processes such as those needed for glasswork.

In the 1950s, the kiln sitter was invented, which allowed for kilns to automatically shutoff once they reached a specified temperature.

The Automatic Kiln Controller Revolution: 1986 – Present

The Digital Age brought with it the invention of the automatic kiln controller, which could be programmed in advance to carry out entire firing schedules without user input. While early automatic controllers were complicated and difficult to operate, they still significantly streamlined the firing process.

In 2015, SDS Industries revolutionized the automatic kiln controller industry with the release of the TAP Kiln Controller – the first commercially available consumer kiln controller to utilize an intuitive, graphical user interface. Using touchscreen technology, the TAP Kiln Controller allows users to easily operate their kiln and create, edit and save an unlimited number of firing schedules and steps. Additionally, the TAP Controller allows users to quickly check the status of their kilns with easy-to-read indicators and push notifications to their mobile devices.

User Interface from a TAP Digital Kiln Controller — **SDS Industries released the TAP Kiln Controller in 2015.**

In 2017, SDS Industries released the first iteration of the TAP Kiln Control Mobile App, which allowed users to remotely monitor and control their kiln from their mobile device – another major leap forward for the kiln control industry. Since then, SDS Industries has continued to be at forefront of kiln control innovation with updates to their mobile app, the release of TAP II Controllers with built-in Wi-Fi integration, as well as the upcoming releases of TAP Monitor, TAP & Go, and TAP Micro.

Enjoy Most Advanced, User-Friendly Automatic Kiln Controllers

The TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use automatic kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

We invite you to explore our selection of automatic kiln controllers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP-Controlled Kilns and Heat Treat Ovens through one of the following distributors:

Posted on June 20, 2023August 9, 2023 by Scott Shannon

Types of Kilns: An Informative Guide for Kiln Users

Kilns have been used for millennia to create ceramic, glass, and even metal objects. As technology has advanced, so have kilns. Now, there are a wide variety of kilns available on the market for hobbyists and professionals alike. In this guide, we’ll explore the different types of kilns and their specific uses.

What Is a Kiln?

Before getting into the distinctions between the different types of kilns, let’s reach a broad definition for what a kiln is. A kiln is an insulated chamber that can be heated to very high temperatures for firing, burning, or drying of pottery, ceramics, glass, metals, or other materials.

Types of Kilns: Overview

As human civilization has evolved, the kiln has undergone many iterations. There are multiple ways to categorize kilns. For instance, you can categorize kilns based on power source, heat distribution, structure or technique, use-case or size, material fired, or control method. Below is a quick overview of the various types of kilns. Later in the article, we’ll be exploring the most common types of modern kilns more in-depth.

Types of Kilns Based on Power Source

Wood-Fired Kilns: Wood-fired kilns use heat from burning wood to increase the temperature of the kiln.
Coal-Fired Kilns: Coal-fired kilns, which used coal to replace wood for the fuel source, were widely used up until in the mid-twentieth century.
Gas Kilns: Gas kilns use natural gases or propane to heat materials and are capable of reaching high temperatures that exceed the temperatures of wood burning or electric kilns.
Electric Kilns: The most common type of kiln for artists and hobbyists, electric kilns use electric current to heat elements inside the kiln, offering more precise control over temperature.

Types of Kilns Based on Heat Distribution

Intermittent Kilns: Intermittent, or periodic, kilns are only heated some of the time. With intermittent kilns, the ware is placed inside the kiln and the internal temperature of the kiln is increased or decreased based on a firing schedule. However, once the firing is complete, the ware and the kiln itself are allowed to fully cool.
Continuous Kilns: Continuous kilns are perpetually heated. Continuous kilns, or tunnel kilns, have a continuous heat source in the center. Ware is physically moved throughout the kiln, closer or farther to the heat source, to control its temperature. Continuous kilns are more commonly used for industrial processes.
Updraft Kilns: Updraft kilns are heated from the bottom of kiln and air is exhausted from the top.
Downdraft Kilns: More efficient than updraft kilns, downdraft kilns are also heated from the bottom, but the construction of downdraft kilns forces the hot air to recirculate the kiln rather than escaping from the top.

Types of Kilns Based on Structure or Technique

Pit Fire Kilns: The earliest iteration of the kiln, pit fire kilns are wood burning kilns that rely on earthen pits to provide insulation.

Beehive Kilns: Beehive kilns, another early iteration of wood burning kilns, utilize arches to create a domed brick chamber for firing. Beehive kilns included baffles to regulate airflow and control the temperature of kiln, as well as holes at the top of the chamber (and later chimneys) to allow the heat to rise.

A beehive kiln in Death Valley, CA — **Beehive kilns were one of the earliest evolutions of wood burning kilns.**

Climbing Kilns: Climbing kilns were built into hillsides. A fire would be lit at the bottom and, since heat rises, the temperature of the kiln would increase with greater regularity, allowing for greater quantities of pottery to be fired.

Soda Kilns: Soda kilns use large, arched chambers, with a chimney on one end, and are heated to high temperatures. During firing, sodium bicarbonate dissolved in water is sprayed onto the ware to form a glaze.
Sawdust Kilns: Sawdust kilns are simplistic kilns that consist of a small brick chamber where bisque is covered in sawdust. A grate is used to cover the top of the kiln, and the fire is lit on top of the grate.
Anagama Kilns: Originally invented in China and later brought to Japan, Anagama kilns are wood-burning kilns that consist of a sloped earthen structure with a single fire chamber on one end and a chimney on the other.
Noborigama Kilns: An evolution of the Anagama kiln, Noborigama kilns are multi-chambered wood-fired kilns that consist of a succession of chambers with a stoked fire at the lowest level. More efficient than Anagama kilns, Noborigama kilns capture and recirculate the hot air from previous firings.
Raku Kilns: Raku is a firing technique where the ware is removed from the kiln while the kiln is still hot. As such, Raku kilns must allow for the ware to be easily removed. Today, most Raku kilns are gas powered since electric kilns can be damaged by opening them when the kiln is at temperature.
Top Hat Kilns: Top hat kilns are designed so that the firing chamber is lowered down onto the wares and then raised again when firing is complete, often using a hand-crank.
Bottle Kilns: An evolution of the beehive kiln, bottle kilns (or bottle ovens) are coal-fired kilns made from brick that consist of a hovel that tapers into distinctive bottle-shaped chimney – hence the name! The unique shape of the bottle kiln improved draught while protecting wares from inclement weather.

Car Kilns: Typically used for industrial processes, car kilns utilize a static firing chamber, through which wares are moved on a wheeled cart. Smaller scale car kilns are occasionally used by schools or potteries.
Front-Loading Kilns: Front-loading kilns, or side-loading kilns, have a hinged door built into the front of the kiln. Wares are loaded horizontally into the kiln.
Top-Loading Kilns: Top-loading kilns have a hinged door built onto the top of the kiln. Wares are lowered down into the kiln, making it easier to ensure they’re centered.

Types of Kilns Based on Material Fired

Glass Kilns: Glass kilns are specifically designed to heat glass to very precise temperatures so it can be fused, slumped, or cast.
- - Annealing Kilns: Annealing kilns are used to slowly cool down glass to improve its durability and prevent the glass from experiencing thermal shock.
Ceramic Kilns: Ceramic kilns, or pottery kilns, are used to fire pottery, clay, and other ceramic materials.
Knife Kilns: Knife kilns, also commonly referred to as heat treat ovens, are designed to heat treat blades to increase their hardness, improve their durability, or otherwise alter their physical properties.

A ceramic kiln is a type of a kiln used for firing pottery and ceramics. — **Ceramic kilns are usually more tall and cylindrical since pottery can be stacked during firing.**

Types of Kilns Based on Use-Case

Hobby Kilns: Hobby kilns tend to be smaller and less expensive, intended for home or studio use by artists and crafters. Depending on their size and design, hobby kilns can be used for a variety of applications, ranging from firing single quantities of small ceramics and glassware to firing small batches of wares or more large-scale pieces.
Industrials Kilns: Industrial kilns are much larger and more powerful, designed to handle large quantities of materials in industrial settings. Designed for production and commercial use, industrial kilns are used to fire larger quantities of materials or for processes that require higher temperatures.
Small Kilns: Small kilns are small, transportable kilns, for firing a small quantity of material. They are typically used by hobbyists who work in a home or studio setting and have limited space. Typically ranging between .6 and 6 cubic feet, small kilns can be used for a variety of applications, such as making jewelry and small ceramic pieces to slightly larger wares.

Small kilns are small, transportable kilns, for firing a small quantity of material. — **Small kilns range from .6 to 6 cubic feet. The smallest small kilns are better suited for making jewelry, small plates, and other small wares.**

Large Kilns: Large kilns are large, often permanently installed, kilns that are designed for industrial or commercial use and can handle much larger quantities of materials. Typically larger than 9 cubic feet, large kilns can be used to accommodate a much wider range of applications.

Types of Kilns Based on Control Method

Automatic Kilns: Automatic kilns, or digital kilns, use automatic temperature controllers to execute the firing process and control the temperature of the kiln without user input.
Manual Kilns: Manual kilns rely completely on user input in order to execute a firing schedule, although they may sometimes utilize a device known as a kiln sitter to power off the kiln when it’s reached a specific temperature.

Traditional Kilns: The Evolution of Wood Burning Kilns

The first kilns, developed nearly 10,000 years ago, were extremely rudimentary. They consisted of a hole or trench that was dug into the ground and filled with combustible materials. Pottery was stacked within the flames, and the insulation of the earth allowed the pottery to reach high enough temperatures to fire. This technique, known as pit firing, was extremely sporadic and unpredictable, often resulting in shards of broken pottery.

Wood burning kilns and, later, coal burning kilns, remained the standard up until the industrial revolution. However, over the centuries, technology for wood burning kilns continued to evolve, resulting in greater precision and temperature control. Pre-industrial advancements in kiln technology include beehive kilns, climbing kilns, soda kilns, sawdust kilns, bottle kilns, car kilns, and Anagama kilns – all of which leverage changes in elevation, airflow, and distance from the heat source to better regulate kiln temperature.

Comparisons of Modern Kilns

While a few contemporary artists and specialists still use wood-fired kilns and traditional firing methods, the industrial revolution introduced the modern kiln, which uses gas or electricity to produce heat. Modern kilns come in a variety of configurations for a variety of applications – from large industrial kilns that are big enough to fill a room to tabletop kilns that are about the size of a toaster oven!

Hobby Kilns vs. Industrial Kilns

The first major distinction between types of kilns is whether they are designed for hobby or industrial use. Hobby kilns tend to be smaller and less expensive than industrial kilns (typically ranging from $700-$2,000 dollars), intended for home or studio use by artists and crafters. These kilns are often electric and digital, making them easy to use and control.

In contrast, industrial kilns are much larger and more powerful, designed to handle large quantities of materials in industrial settings. Industrial kilns can cost tens of thousands or even hundreds of thousands of dollars! Industrial kilns can be electric or gas-powered and may have more complex controls. These kilns play a crucial role in many manufacturing processes and are essential for producing a wide range of products that we use every day.

Small Kilns vs. Large Kilns – Is There a Difference in Performance?

Small kilns vs big kilns…it’s all relative, right?! For this case, let’s think of small kilns as being used by hobbyists who work in a home or studio setting and have limited space. These kilns are typically designed to fire a small quantity of materials at a time and can be easily transported. Big kilns, on the other hand, are designed for industrial use and can handle much larger quantities of materials. They are often permanently installed and require a dedicated space.

But to answer your question – yes. Kiln size can affect performance in several ways:

Temperature Distribution: Large kilns may have more difficulty maintaining a consistent temperature throughout the entire kiln due to increased heat loss from the larger surface area. This can lead to uneven firing, resulting in variations in color and texture of the fired pieces.
Fuel Consumption: Large kilns require more fuel to maintain the desired temperature, which can increase operating costs.
Production Capacity: The size of the kiln will determine the maximum size and number of pieces that can be fired at one time, which can impact production capacity.
Heat-Up and Cooling Times: Large kilns may take longer to heat up and cool down than a small kiln, which can affect the overall time it takes to complete a firing cycle.
Maintenance: Large kilns may require more frequent maintenance and repair than small kilns due to the increased wear and tear on the components.

Overall, the size of the kiln is an important factor to consider when determining the performance of a kiln. The optimal size of the kiln will depend on the specific needs and requirements of the user.

Gas Kilns vs. Electric Kilns

When it comes to modern kilns, another big distinction is the power source.

Gas kilns use natural gas or propane to heat the materials being fired. These kilns are often used by industrial manufacturers who need to fire large quantities of materials quickly. Gas kilns can reach higher temperatures than electric kilns, making them ideal for certain types of projects.

Electric kilns, on the other hand, use electricity to heat the materials being fired. They are often used by hobbyists and artists who need more control over the firing process. Electric kilns are typically smaller and more affordable than gas kilns, making them a popular choice for home use.

Manual Kilns vs. Digital Kilns

When using a manual kiln, the operator must manually control the temperature and other variables during the firing process, rather than relying on automated controls. This can involve adjusting the fuel source, opening and closing vents, and monitoring the temperature with a thermometer. Manual kilns are often used by artists and craftspeople who prefer a hands-on approach.

Digital kilns, on the other hand, use a programmable digital controller to automatically carry out the firing schedule without direct user input. Modern digital controllers, such as TAP Controllers from SDS Industries, are fine-tuned, intuitive, and provide constant communication and feedback to users. The controllers allow for precise temperature control and can be programmed to follow specific firing schedules.

Differences between Glass Kilns, Ceramic Kilns, and Knife Making Kilns

Different types of kilns are optimized for specific materials. Glass kilns, ceramic kilns, and knife making kilns are made to meet the unique properties of each of these materials and the way they react to heat. Here are some of the main differences in these kiln types:

Temperature Range

Glass kilns are typically used for melting and shaping glass at temperatures ranging from 1,1000 to 1,800 degrees Fahrenheit.
Ceramic kilns are used for firing ceramics at temperatures ranging from 1,800 to 2,400 degrees Fahrenheit.
Knife making kilns are used for heat-treating steel at temperatures ranging from 1,500 to 2,200 degrees Fahrenheit.

Heating Elements

Glass kilns often use heating elements made from molybdenum wire.
Ceramic kilns often use heating elements made from Kanthal wire.
Knife making kilns may use heating elements made from Kanthal or nichrome wire.

Firing Cycles

Glass kilns may have longer firing cycles with slow heating and cooling rates.
Ceramic kilns may have shorter firing cycles with faster heating and cooling rates.
Knife making kilns may have a shorter firing cycle but a longer hold time at the peak temperature to allow for the desired heat treatment of the steel.

Firing Environment

Glass kilns often use a controlled atmosphere to prevent oxidation and maintain consistent heating.
Ceramic kilns may use a reduction atmosphere to enhance the glaze or surface finish of the fired ceramic.
Knife making kilns may have an inert atmosphere to prevent oxidation of the steel.

Size and Shape

Glass kilns come in all shapes and sizes, from small, table-top units to large, elongated kilns.
Ceramic kilns also come in a variety of shapes and sizes but are typically more cylindrical, since you can stack ceramic during the firing process.
Knife making kilns may be smaller and have a long, narrow shape to accommodate blades or other small metal objects.

A 3D rendering of a knife making kiln — **Knife making kilns and heat treat ovens are used for making knife blades or for other metal heat treatments.**

Conclusion

There you have it! Like we mentioned in the beginning, the kiln has undergone many different iterations throughout its history, but hopefully now you have a better understanding of the different types of kilns.

If you’re in the market for a new kiln, we encourage you to check out the kilns available at one of our partners:

And if you’re looking for the most advanced, precise, and easy-to-use automatic kiln controllers to pair with your electric kiln, we invite you to check out the TAP and TAP II Controllers by SDS Industries! With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers are the most advanced, precise, and easy-to-use automatic kiln controllers on the market today. TAP Controllers can pair with any relay-controlled kiln to help streamline the firing process and give you greater control over your projects.

We invite you to explore our selection of automatic kiln controllers, standalones, and conversion kits on our online store.

Posted on June 13, 2023October 2, 2023 by Brittany Gabel

Complete Guide to Kiln Safety for Your At Home Kiln

When it comes to kilns, it’s safety first! With proper precautions, using an at home kiln can be an extremely safe and rewarding experience. But when temperatures run, you don’t want to take chances!

Kiln safety has three main phases: Installation, Operation, and Maintenance. In the guide below, we’ll be covering each of those phases more in-depth and providing tips for safe, seamless kiln firings.

Steps for Kiln Safety During Installation

Kiln safety starts with proper installation. When installing an at home kiln, there’s a couple things to keep in mind:

Select a space with proper flooring: Kilns get hot! Make sure to select a space with level flooring that’s non-combustible and able to withstand high temperatures. Concrete, tile, and linoleum floors will be more heat resistant than wood, vinyl, or carpet. Never leave your kiln directly on the floor. Always use the manufacturers included stand to ensure safe clearance from the floor below. Note: The same principles apply for table top kilns – make sure not to install them on flammable surfaces or tables.
Ensure proper clearance: Speaking of clearance, it’s extremely important that you give your kiln room to breathe. It’s recommended that your kiln should be located at least 18″ from non-combustible surfaces and 36” from combustible surfaces. (Note: This includes opening the lid to your kiln, so make sure to account for that as well during installation.)
Make sure the space is proper ventilated: Depending on the material you’re firing, your at home kiln may emit toxic gases or irritants like carbon monoxide, carbon dioxide, sulfur dioxide, or chlorine. Definitely things you don’t want to breathe! These gases may impair your health or even interfere with your ability to safely operate your kiln, so it’s important to make sure your kiln is properly ventilated and that respirators are used when dealing with noxious fumes.
Install your kiln in a dry area: Electricity and water don’t mix. If you’re using an electric kiln, it’s important to make sure you don’t install your kiln in an area that’s damp or exposed to moisture. Additionally, water can cause corrosion, which will reduce the life of your at home kiln components.
Follow manufacturer guidelines for installation: When you purchase your kiln, you should receive manufacturer guidelines for installation and kiln safety. Make sure to adhere to these closely when installing your kiln. If you purchase a used kiln, contact the manufacturer for installation guidelines.
Get any electric work done by a qualified electrician: At home kilns, especially larger ones, utilize a lot of electricity, so it’s important to make sure that you use a dedicated circuit with a properly rated power outlet and never use an extension cord. During kiln installation, it’s recommended that you enlist the help of a certified electrician to make sure your at home kiln is safely installed.
Make sure thermocouples are properly installed: Thermocouples help your automatic kiln controller precisely regulate the temperature of your kiln. However, thermocouples will only give you accurate temperature readings if they’re properly installed! Thermocouples should be inserted an inch or two into the interior or your kiln and should have at least 1″ clearance from any shelves, components, or any materials you place inside your kiln.
For DIY kiln builds, make sure relays are properly installed: Kiln relays ensure the safety of your kiln by cutting power to the elements if the kiln gets too hot. For DIY kiln or oven builds, it’s important to choose the right type of relay; for instance, solid-state and mercury relays will have far more longevity and reliability than mechanical relays. But it’s even more important to make sure that relays are properly rated and installed and that you utilize a safety relay to add redundancy in case one relay fails.
Don’t forget to check with your homeowners or business insurance carrier for any limitations or policy changes resulting from kiln use: Installing an at home kiln may affect your homeowners or business insurance policy – make sure to check with your provider to protect your financial safety!

Steps for Kiln Safety During Operation

Now that you have your at home kiln safely installed, it’s important to know kiln safety best practices for operation and firing:

Always use personal protective gear: During kiln firing, it’s important to use personal protective gear to ensure your safety. Kiln mitts or heat resistant gloves should be used when handling your kiln during firing, and dark, protective eyeglasses should be used to protect your eyes when looking into the kiln peepholes or when opening the lid.
Keep a fire extinguisher nearby: High temperatures increase risk of fire, so it’s always recommended to keep a fire extinguisher on hand beside your at home kiln.
Do not leave your kiln unattended during firing: Although modern digital kiln controllers provide temperature safety shutoff, alerts, alarms, and the ability to monitor and control your kiln remotely from your mobile device, it’s still recommended to never leave your kiln unattended during firing.
The TAP Kiln Control Mobile App allows you to monitor the status of your kiln, control your kiln remotely, and review error reports.
Exercise caution if you need to open lid or door when your kiln is operational: Occasionally, it may be necessary to open the lid or door on your at home kiln while the kiln is operational. But when you do so, exercise extreme caution! Always wear protective gear and stand to the side of the lid or door whenever possible.
Let kiln cool before unloading: Even after your kiln completes a firing schedule, it can remain hot for hours. Always let your at home kiln cool completely before unloading. It’s also important to let your wares cool inside the kiln to prevent them from being cracked by abrupt changes in temperature.
Do not place combustible materials on or near the kiln: Before firing, always check to make sure your at home kiln still has proper clearance. Prior to and during firing, make sure not to leave anything on top of or next to your kiln.
Do not leave your kiln unattended near children or pets: Even if you’re aware of proper kiln safety procedures, it doesn’t mean that your children or pets will exercise the same precaution. Do not leave your kiln running in an area where children or pets will have access.
Wash your hands after handling: Thoroughly washing your hands after handling your ware keeps you from potentially ingesting toxic materials.

Kiln Maintenance and Upkeep

Kiln safety isn’t just limited to installation and operation. Regularly maintaining your at home kiln will ensure safety and prolong the life of your kiln components:

Clean the kiln between firings: Between firings, clean your kiln to ensure there is no residue or debris.
Always unplug your kiln before making repairs: Always unplug your at home kiln when making repairs or modifications. For additional safety, it may be prudent to leave your kiln unplugged any time you’re not using it.
Regularly inspect electrical components: Regularly inspect the electrical components of your at home kiln for discoloration, brittleness, or corrosion. Immediately replace these components if necessary.
Regularly replace thermocouples: In order to ensure accurate temperature readings for your at home kiln, it’s recommended to replace Type K Thermocouples every 30 to 50 firings.
Invest in digital controllers that have advanced onboard diagnostics and preventative maintenance alerts: Manual inspection has its limitations. Advanced digital kiln controllers like the TAP and TAP II Controllers from SDS Industries include onboard diagnostics, enhanced data logging, and preventative maintenance alerts to help you stay up-to-date on kiln maintenance.

The Role of TAP Automatic Kiln Controllers in Ensuring Kiln Safety

Even with all of these kiln safety tips, the safety of your at home kiln is also determined by the quality of your kiln components and the precision and reliability of your kiln controller. At SDS Industries, we are dedicated to providing the most advanced, precise, reliable controllers for your at home kiln, oven, or furnace. But more than that, we equip our controllers with features and functionalities that enhance kiln safety. These kiln safety features include:

PID-driven precision to ensure that your kiln precisely adheres to its intended firing schedule with fast response, minimal overshoot, and limited steady-state error.
Max temperature safety shutoff to ensure your kiln doesn’t surpass its rated temperature.
Integration with the TAP Kiln Control Mobile App to provide you with advanced diagnostics, abort firing, and preventative maintenance alerts – so you have insight into your kiln firings even if you have to step away from your project.
Preventative maintenance alerts, with relay, thermocouple, and element life reporting.
Kiln error information and diagnostic features to keep you informed of any past, present, or future kiln component failures.

Introducing TAP Monitor Digital Pyrometer

Additionally, as part of our dedication to kiln safety, SDS Industries is excited to announce the TAP Monitor Digital Pyrometer. Available as a standalone device that plugs right into your kiln, or as configurable components for installation, the TAP Monitor Digital Pyrometer adds precise temperature readings, remote monitoring, push notification alerts, and safety redundancy to any relay-controlled kiln or oven.

The TAP Monitor seamlessly integrates with the TAP Kiln Control Mobile App to let you remotely monitor the status of your kiln from your smartphone, watch, or tablet – regardless of what controller your kiln uses. These features will enhance kiln safety for manual or automatic kilns and add safety redundancy and max temperature shutoff in case of relay failure.

The TAP Monitor Digital Pyrometer will be releasing soon, but you can already preorder your standalone unit here or as a set of configurable components for DIY installs here.

Choose the Most Advanced, User-Friendly Automatic Kiln Controllers

For added kiln safety and ease-of-use, the TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use automatic kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

Posted on June 6, 2023July 3, 2023 by Scott Shannon

What is a Kiln Sitter?

Before the invention of automatic kiln controllers, the kiln sitter was a major innovation in kiln control technology. Introduced in the 1950s, a kiln sitter is a mechanical device that automatically shuts off a manual kiln when it has reached a specified temperature.

Unlike digital controllers, which utilize thermocouples, control algorithms, and microchips to precisely monitor kiln temperature and regulate power, kiln sitters utilize more primitive technology to determine when the kiln has reached temperature: melting and gravity!

Components of a Kiln Sitter

Before explaining the mechanisms of how a kiln sitter determines when to shut off power to the kiln, it’s important to understand the various components of a kiln sitter:

Cone Supports: Two cone supports in the interior of the kiln are used to support the sitter cone.
Sitter Cone: The sitter cone (or witness cone) is a small pyrometric cone that is placed on top of the cone supports and used to prop up the sensing rod.
Sensing Rod: The sensing rod is a metal rod that connects the interior of the kiln to the exterior components of the kiln sitter. On the interior side of the kiln, the sensing rod is propped up on top of the sitter cone. On the exterior side of the kiln, the sensing rod is connected to a claw assembly that holds up the weighted latching mechanism.
Weighted Latching Mechanism: The weighted latching mechanism, on the exterior of the kiln, is connected to the sensing rod at the top of the latch. The bottom of the latch is a weighted hinge that will naturally fall unless held in place by the claw assembly.
Timer: A timer on the exterior of the kiln sitter shuts off the kiln when the timer hits its allotted time.
Plunger: Situated within the weighted latching mechanism when the latching mechanism is flipped up into the on position, the plunger is depressed so that the timer is initiated.

How a Kiln Sitter Works

On the interior of the kiln, the sensing rod is propped up by the sitter cone. While the sensing rod is propped up, it lowers the claw assembly to hold up the weighted latching mechanism on the exterior of the kiln, allowing the kiln to be powered on.

However, as the kiln heats up, the sitter cone begins to melt at a specified temperature, allowing the sensing rod to move lower under the weight of gravity. As the sensing rod lowers, the assembly claw is lifted. When the sitter cone melts to a 90° angle, the sensing rod is fully lowered, the assembly claw is fully raised, and the weighted latching mechanism falls, causing the kiln to power off.

Illustration of the position of the sensing rod when the sitter cone is melted. — **When the sitter cone has melted to a 90° angle the sensing rod is fully lowered, and the kiln is powered off.**

How to Use a Kiln Sitter

Using a kiln sitter is extremely easy. Below is a step-by-step guide:

Select a sitter cone that matches the pyrometric cone temperature rating for the ceramic or other material you’re firing. Different materials have different firing temperatures. Select a sitter cone that matches the cone temperature of your material. This ensures that your sitter cone will melt and power off the kiln at the correct temperature.
With one hand, hold up the weighted latching mechanism and attach it to the claw assembly. Make sure that there is proper clearance between the weighted latching mechanism and the claw assembly (usually 1/16th of an inch). The two should not be touching at the start of the kiln firing.
With your other hand, insert the sitter cone between the cone supports and the sensing rod. Make sure the sitter cone is placed evenly on top of the cone supports. It’s also important to center the sitter cone on top of the cone supports (unless you’re intentionally aiming for an abbreviated or a prolonged fire).
Once the sensing rod is situated on top of the sitter cone, set the timer of the kiln 30 to 60 minutes passed the projected time it will take your sitter cone to fully melt. This is to ensure redundancy in case there is an error with the kiln sitter.
Power on the kiln and press the plunger to initiate the timer. You’re ready to go! At this point, the kiln sitter should make sure the kiln powers off at the proper time – but the timer switch is there as backup just in case.

Limitations of a Kiln Sitter

When it was first introduced, the kiln sitter was a major advancement in kiln control technology. However, that was over 70 years ago, and there have been major advancements in kiln controller technology since then. While a kiln sitter is adequate for simple firings, such as those for pottery and ceramics, it is not nearly as precise, versatile, or handsfree as the most advanced digital kiln controllers.

Limitations of kiln sitters include:

Incapable of complex kiln firings with precise ramp rates and multiple setpoints, such as those needed for glasswork.
Leaves room for user error – for instance, improperly positioning the sitter cone and cause the firing to go on for too long or not long enough.
Doesn’t provide extensive diagnostic insight into failed firings.
Requires the kiln operator to manually check the status of their kiln.

Automatic kiln controllers, on the other hand, perform all the functions of a kiln sitter but with a greater degree of accuracy, control, insight, and less need for direct oversight or manual intervention.

How Hard Is It to Upgrade Your Kiln Sitter to an Automatic Controller?

The good news is that you can upgrade your kiln sitter-controlled kiln to automatic controls without having to replace your kiln or make significant modifications. Standalone kiln controllers make it easy to upgrade your kiln sitter – check out our step-by-step guide for DIY standalone kiln controller installation!

Choose the Most Advanced, User-Friendly Automatic Kiln Controllers

If you’re tired of the limitations of a kiln sitter, the TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use automatic kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Controller Mobile App, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

Posted on May 30, 2023July 3, 2023 by Scott Shannon

Kiln Controller DIY: Complete Guide to Kiln Controller Installation

Excited to upgrade your kiln controller, but intimidated by the prospect of kiln controller DIY installation? The good news is that DIY kiln controller installation is probably easier than you think. You definitely don’t need an engineering degree to do it!

Options for DIY Kiln Controller Installation

When it comes to DIY kiln controller installation, the complexity of your installation depends on your application. Typically, you’ll be looking at three different options:

Standalone Kiln Controllers: Standalone kiln controllers are the easiest option for DIY installation. Typically used for upgrading a manual kiln to digital controls, standalone kiln controllers include the necessary transformer, electrical receptacle, relays, and thermocouples, making them a fairly ‘plug-and-play’ solution.
Conversion Kits: Conversion kits are used for replacing an existing automatic kiln controller. Conversion kits include a kiln controller, wiring harness, and a faceplate, allowing you to swap out kiln controllers with no (or minimal modification) to your kiln. No splicing or knowledge of wiring diagrams required!
Kiln Controller Units for DIY Builds: This is where things get a little more complicated. For these types of kiln controller DIY installations, you typically purchase a kiln controller that only includes a faceplate and a wiring harness pigtail. This means that you’ll have to purchase thermocouples separately and splice the wiring from the new controller unit to the right wires from your DIY kiln, furnace, or oven build.

But don’t worry! We’ll be covering each of these installation types more in-depth so that you’ll be equipped for your own DIY kiln controller installation.

Steps for Standalone Kiln Controller Installation

Like we mentioned earlier, standalone kiln controllers provide the most straightforward installation process for DIYers. Below are the steps for DIY kiln controller installation for standalones:

Mount your standalone kiln controller unit. First, you’ll have to figure out where you want to place your standalone kiln controller unit in relation to your kiln. Standalone controllers are available in table top and wall mount configurations. Table top standalone kiln controllers are easier to mount – you just place the unit on top of a flat surface! With wall mount kiln controllers, you will have to drill into the wall or other vertical surface to mount your unit.
Run the thermocouple to the inside of your kiln. Next, you’ll want to run the wire for the thermocouple so that the tip of the thermocouple is inserted into the interior of your kiln or oven. This may involve having to drill a small hole through your kiln brick.
Plug your kiln into your standalone kiln controller unit. Take the plug from your kiln or oven and plug it into your standalone kiln controller. This way, your kiln controller will be able to manage the power flow to the elements of your kiln in order to regulate temperature.
Plug your standalone kiln controller unit into a wall outlet or other power source. When purchasing a standalone kiln controller for DIY installation, you’ll have the option to select different plug types, which need to be compatible with your current kiln plug. But the NEMA 5-15 plug is the standard plug in North America, which will plug into any wall outlet or extension cord already in your house!

At this point, your DIY kiln controller installation is complete, and your standalone unit is ready to control the temperature of your kiln. Just power on your kiln, and you’re good to go!

Using Conversion Kits for a DIY Kiln Controller Upgrade

Conversion kit installations are usually only slightly more complicated than using a standalone unit. Below are the steps for a kiln controller DIY installation using a conversion kit:

Make sure to purchase a kiln controller conversion kit that’s compatible with the wiring and controller housing for your current controller. Before purchasing a kiln temperature controller conversion kit, you need to know whether your current kiln controller is a 3-key, 12-key, or smart controller. So how do you tell the difference? Easy, just look at the inputs on your current controller. A 3-key controller has three input buttons; a 12-key controller has 12, and a smart controller uses a touchscreen. (SDS Industries includes drop down menus on their conversion kit shop pages, so that you can select the controller you’re replacing to ensure a perfect match. Also, it’s important to note that TAP Kiln Controller Conversion Kits can be used to replace automatic kiln controllers from other manufacturers, such as Bartlett, Orton, Paragon, and Skutt.)
Remove the old automatic controller from your kiln. Removing your old kiln controller is usually fairly straightforward. You should find four mounting screws on the corners of your old unit. Remove these mounting screws using a socket driver or a Phillips head screwdriver. Remove your old controller unit from its housing, detach the thermocouple leads from your old controller, and remove the wiring harness that connects your old controller to your kiln.
Install the new controller mounting box. Your DIY kiln controller conversion kit should include a mounting box to house your new controller. Snake the thermocouple leads and wiring through the middle of the mounting box and screw in the mounting box to your kiln (occasionally, it may be necessary to drill new holes to screw in the mounting box; however, this is only in rare cases, and will be the only modification needed to your kiln or oven).
Plug the new wiring harness adapter into your kiln. The wiring harness adapter for your new kiln controller will plug right into your kiln’s existing wiring harness.
Reattach the thermocouple leads to your new controller. The plug-in for your thermocouple lead will be marked on the controller board of your new controller.
Attach the wiring harness adapter to your new controller. You will find plugs in the back of your controller that match the plugs on the new wiring harness adapter.
Screw in the new controller faceplate to your controller mounting box. Voila! Your kiln controller DIY installation is complete!

Video Walkthrough for Kiln Controller DIY Installation with a Conversion Kit

In the video below, our partners at Kiln Frog walk you through installing a TAP Kiln Controller Conversion Kit:

Kiln Controller Installation for DIY Oven Builds

Finally, for true DIYers, you have the option to purchase kiln controllers and kiln controller components to install your new controller on your kiln or oven build. These installations typically require more technical prowess. For instance, on a true DIY build from scratch, you will need to run the wiring from your main power supply to your power transformer, heating elements, relays, etc., and then splice the correct wirings to your kiln controller.

Or, alternatively, if your kiln or oven is already wired, you would need to splice the existing wiring to your new controller and make any necessary adjustments to your controller housing to accommodate the new kiln control unit.

TAP II and TAP Micro Wiring Schematics

While these types of DIY kiln controller installations are too diverse to provide a standardized step-by-step guide, we’ve included wiring schematics for TAP II Kiln Controllers and TAP Micro Kiln Controllers below. Using these for reference, you should be fully equipped for your kiln controller DIY installation.

TAP II Kiln Controller Wiring Diagrams

TAP II Wiring Diagram – 240VAC, 30A w/ Safety and SSR

TAP II Wiring Diagram – 240VAC, 30A

TAP Micro Kiln Controller Wiring Diagrams

TAP Micro Wiring Diagram – 240VAC, 30A w/ Safety and SSR

TAP Micro Wiring Diagram – 240VAC, 30A Dual SSR

Choose the Most Advanced, User-Friendly Controllers for Your DIY Kiln Controller Installation

If you’re looking to upgrade your kiln or oven build, the TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and the most advanced kiln controller software, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

Posted on May 23, 2023October 23, 2023 by Scott Shannon

How to Manage Your Kiln Firing Schedule

What’s one thing potters, ceramicists, glass artists, and metal workers have in common? Each relies on a kiln firing schedule to produce their finished ware. As you can imagine, kiln firing schedules are not one-size fits all! After all, specific temperatures over specific time periods create specific results.

Below we’ll be exploring the ins and outs of firing schedules – from creation to execution. And we’ll also be looking at how automatic kiln controllers help artists create, manage, and organize their firing schedules.

What Is a Kiln Firing Schedule?

Step #: This represents the order in which the steps of the schedule occur.
Ramp Rate: The speed at which the kiln is heated up or cooled down (measured in degrees per hour).
Setpoint: The desired temperature the kiln reaches during each step.
Hold Time: Also, known as a ‘soak,’ this is the length of time the kiln stays at a specific temperature.

Kiln firing schedules range from extremely simple to extremely complex. For example, some heat treatments for metal may only require a single step with a single setpoint, whereas firing schedules for pottery or glass can include half a dozen steps that require extremely precise inputs and outputs.

Furthermore, different processes for different materials require a specific firing schedule. This may seem like a lot to juggle – and, in the old days, it used to be! In the age of manual kilns and early automatic controllers, kiln operators used to have to shuffle through their firing journals to replicate a specific firing schedule.

Luckily, however, automatic kiln controllers have made creating, managing, and executing firing schedules significantly easier and more streamlined. Modern digital kiln controllers like the TAP, TAP II, and TAP Micro Kiln Controllers by SDS Industries, allow users to select from premade firing schedules or create their own with just a few swipes of their finger from the device’s touchscreen. Additionally, with the TAP Kiln Control Mobile App, users have the ability to create and modify schedules from their smartphone or tablet – or even execute their firing schedule remotely with a premium subscription.

How to Create a Kiln Firing Schedule

SDS Industries designed and launched the original TAP Kiln Controller in 2015 – in large part because we were frustrated with how dang difficult it was to create kiln firing schedules (and then find them later) on the automatic kiln controllers on the market at the time.

A big part of our focus was on streamlining the user experience for firing schedule creation and execution. And, starting from scratch, we had the opportunity to include all the features we’d always wanted on a kiln controller, such as:

An intuitive graphical UI and responsive touchscreen controls.
Logically arranged menus with full text displays to make it easy to create new firing schedules or modify existing schedules.
Alpha-numeric organization for kiln firing schedules to make finding the right firing schedule easy.
The ability to star your favorite schedules for even quicker access.
The ability to create a theoretically unlimited number of kiln firing schedules, each containing a theoretically unlimited number of steps, so users never have to pick up their firing notebook again (unless they really want to)!
Integration with the TAP Kiln Control Mobile App to allow users to create, modify, and execute kiln firing schedules from their mobile device when their kiln controller is connected to Wi-Fi.

Below, we’ll be looking at how to create a kiln firing schedule on the TAP II Kiln Controller UI (schedule creation on the original TAP Controller is extremely similar):

Step 1: Starting from the ‘Home Screen’

Below is a picture of the home screen on a TAP II Kiln Controller:

To access kiln firing schedules, press ‘Start’ on the right side of the screen.

Step 2: Using the ‘Schedule Selector’ Screen to Access Your Kiln Firing Schedules or Create a New One

On the ‘Schedule Selector’ screen, you have the ability to access all of your existing kiln firing schedules by scrolling through the menu on the left side of the screen. Clicking the ‘Edit Icon’ beside the schedule title allows you to edit that firing schedule. Or, to create a new schedule, click ‘New’ on the right side of the screen.

Step 3: Edit and Add Steps to Your Firing Schedule

Clicking the ‘Edit Icon’ will bring you to the ‘Edit Schedule’ screen:

On this screen, you have the ability to add new steps and edit the Schedule Name, Ramp Rate, Setpoint, and Hold Time for each step. Additionally, you have the ability to set alerts to notify you when your kiln has reached its setpoint or hold time for each specific step. When you’re finished editing your firing schedule, click ‘Save.’

Step 4: Execute Your New Firing Schedule

When you click ‘Save,’ the controller will bring you back to the ‘Schedule Selector’ screen. Select your desired schedule and then press ‘Start.’

From there, your TAP II Controller will automatically execute your new firing schedule. From the ‘Execute’ screen, you’ll be able to monitor exactly where your kiln is in terms of your firing schedule, as well as skip steps, access firing logs, or abort your firing.

Schedule Creation UI for the Original TAP Controller

Our partners at Evenheat provide an overview of the schedule creation UI for the original TAP Kiln Controller.

Where Can You Find Different Kiln Firing Schedules?

Manufacturers and distributors often have common kiln firing schedules already programmed into your controller. However, as we mentioned earlier, schedules aren’t one size fits all. Below are some tried and true firing schedules for various types of materials:

Kiln Firing Schedules for Glass: Kiln firing schedules for Full Fuse Casts, Contour Fusing, Tack Fusing, Slumping, Deep Slumping, Draping, Fire Polishing, Pot Melting, Bubble Squeezing, Wine Bottle Slumping, and Crackling.
Kiln Firing Schedules for Pottery and Ceramics: Kiln firing schedules for Basic Cone 04 Bisque Firing (Earthenware, Stoneware, and Porcelain), Cone 05 Glaze Firing (Earthenware), Cone 05/06 Glaze Firing (Mid-Range Stoneware and Porcelain), Cone 10 Glaze Firing (High Fire Stoneware and Porcelain), and Slow Bisque Firing.
Kiln Firing Schedules for Steel: Hardening and Tempering for Steel.
Thermocycling a Steel Knife: Forging, Normalizing, Grain Refining, Annealing, and Cooling Cycle for Steel Knives.

However, please note that different materials and techniques have specific temperature requirements. We encourage you to do your research and always follow recommendations for cones and temperature requirements from your supplier for glass, clay, stoneware, porcelain, or metal.

Limitations to Firing Schedules

Now that you know how to create a firing schedule, you should also understand the limitations. The physical capabilities of the kiln dictate certain physical limitations that cannot be overcome. The material of the kiln, chamber size, power rating, and thermocouple gauge all contribute to the kiln’s demonstrated performance.

As kilns approach higher temperatures, their ability to heat at defined ramp rates begins to fall off. For instance, a kiln that can heat at a ramp rate of 3600 degrees per hour while at 200 degrees will likely be unable to generate the same ramp rate at 1500 degrees. This is a result of the kiln material and power rating.

Learn More About the Most Intuitive, User-Friendly Kiln Firing Schedule Creation

When it comes to creating kiln firing schedules, the TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use kiln controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and cutting-edge kiln controller software, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.