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Complete Guide to Kiln Firing Temperatures

A definitive guide for understanding kiln firing temperatures.

Whether you work in pottery, glass, or heat treat, kiln firing temperatures play a critical role in achieving your desired result. Reaching the correct kiln firing temperature during each stage of your firing schedule is the difference between successfully completing a project…or creating a total mess!

Why Are Kiln Firing Temperatures Important?

Changes in temperature affect the physical properties of a medium. Heat alters a medium’s molecular structure, potentially affecting its hardness, brittleness, malleability, color, water resistance, and more.

Every kiln firing and heat treat process involves exposing material to heat to transform its physical qualities to give it a desired set of characteristics. Whether that’s transforming green clay to bisque, tempering a blade, or casting glass to fit a mold!

Different materials undergo specific physical (and chemical) changes at specific temperatures – so kiln firing temperatures are super important and vary according to medium and technique.

Kiln Firing Schedules

However, kiln firing temperature isn’t the only factor affecting outcome. The relationship between changes in temperature over time is super important. That’s why kiln firing schedules define the following:

  • Step #: The order in which the different kiln firing temperatures occur.
  • Ramp Rate: The speed at which changes in temperature occur (measured in degrees per hour).
  • Setpoint: The desired temperature the kiln reaches during each step (measured in degrees).
  • Hold Time: The length of time (defined in days, hours, or minutes) the kiln stays at a specific kiln firing temperature before advancing to the next step.

Kiln firing schedules vary greatly in kiln firing temperatures, as well as complexity. For instance, normalizing steel for a handmade knife might only involve a single setpoint over a specific hold time. Whereas, bisque firing pottery might involve five different setpoints, each with a specific ramp rate.

In addition to increases in firing temperature, decreases in temperature are equally important. Often, heating up an object and then cooling it down too rapidly jeopardizes its structural integrity, leading to cracks and brittleness.

Kiln firing 1095 steel to 1600° F relieves internal stress and ensures uniformity, making it stronger and harder.
Normalizing 1095 steel to 1600° F relieves internal stress and ensures uniformity, making it stronger and harder.

 

Categorizing Kiln Firing Temperatures

There are multiple ways to categorize kiln firing temperatures – whether by temperature range, material, process, or cone temperature. Artists in different media generally have different ways of categorizing kiln temperature:

  • Heat Treat: By and large, heat treat artists categorize kiln firing temperatures according to process (hardening, normalizing, tempering, etc.) and material. There are very few “one-size-fits all,” standardized ranges or schedules – specificity is key.
  • Kilnformed Glass: Glass artists categorize temperature according to technique (slumping, casting, fusing, annealing, etc.) and glass “coefficient of expansion” (how fast glass expands based on changes in temperature). Glass thickness is equally important, but that has more to do with changes in hold times or ramp rates as opposed to temperature.
  • Pottery and Ceramics: For pottery and ceramics, kiln firing temperatures are still largely categorized based on cone firing temperatures and ranges – which we’ll be covering more in-depth below! Each ceramic material is rated for a cone that corresponds with a specific temperature, allowing for a more standardized scale.
For a full fuse kiln firing for 90 COE glass, the kiln must reach a setpoint of 1490° F.
For a full fuse kiln firing for 90 COE glass, the kiln must reach a setpoint of 1490° F.
 

 

 Understanding Cone Firing Temperatures

 

Unlike heat treat and glasswork, which require a greater level of specificity, potters deal in pre-defined temperature ranges – which correspond with pyrometric cones. Before the advent of modern programmable digital kiln controllers, kiln temperature control relied on manual kilns and the use of pyrometric cones and kiln sitters to measure when the proper kiln firing temperatures were reached.

Pyrometric cones melt at specified temperatures, providing a range for measuring (and categorizing) kiln firing temperatures. So, for instance Cone 06 for “low fire” clay softens and bends at 1832° F (1000° C), while Cone 14 for “high fire” porcelain softens and bends at 2552° F (1400° C).

Today, digital kiln controllers and digital pyrometers have largely made pyrometric cones obsolete. But cone numbers are still widely referenced for categorizing kiln firing temperatures. While cone firing charts are predominantly used in pottery, they are still sometimes referenced for heat treat and glasswork.

Click the button below for an in-depth cone temperature chart – which notes firing temperatures for each cone and describes the changes clay undergoes at each temperature:

 

Kiln Firing Temperature Ranges in Pottery

As you can see on the cone temperature chart, there are also temperature ranges that are used to categorize kiln firing temperatures for clay. The ranges below also correspond with three different categories of clay: earthenware, stoneware, and ceramics:

  • Low-Fire Clays: Cone 06 – Cone 1: Low-fire clays, also referred to as earthenware, are fired at temperatures ranging between 1828° F to 2079°F.
  • Mid-Fire Clays: Cone 4 – Cone 6: Mid-fire clays, which can be earthenware or stoneware, are fired at temperatures between 2142° F to 2232° F.
  • High-Fire Clays: Cone 10 – Cone 14: High fire clays, which can be used for stoneware or porcelain, are fired at temperatures between 2345° F to 2552° F.
Cone 04 clay, which is a common “low-fire” clay, fires at a kiln firing temperature of 1945° F.
Cone 04 clay, which is a common “low-fire” clay, fires at a kiln firing temperature of 1945° F.

For an in-depth explanation of the different types of clay, check out “Kiln Firing Chart for Pottery and Ceramics [Infographic].”

How to Ensure Your Kiln Reaches the Correct Kiln Firing Temperatures

Now that you understand the importance of kiln firing temperatures, how do you ensure your kiln reaches the correct temperature? That’s where kiln controllers come into play! There are three general phases when it comes to using a kiln controller to manage firing temperatures:

  • Input: First, the user has to enter what temperatures the kiln needs to reach, usually through creating a firing schedule or selecting a pre-set schedule.
  • Execution: Next, the temperature controller automatically executes the schedule, ensuring the kiln reaches the correct kiln firing temperatures over the correct timeframe.
  • Measurement: Throughout the execution phase, it’s important that either the controller itself (or an independent pyrometer) is able to precisely record kiln firing temperature based on input from the thermocouple.

Different kiln control methods handle these three phases more or less effectively. For instance, some temperature controllers are able to precisely execute schedules but are so difficult to use from a User Experience (UX) standpoint that it’s hard to know if you input the correct kiln firing temperatures to begin with! Others allow for too much variability in response times or temperature overshoot, meaning the kiln might not reach the precise temperatures you need during execution. And most kiln controllers require the user to be physically present at the kiln at all times to monitor its temperature.

The TAP Kiln Controllers by SDS Industries were designed to solve all these problems – with a touchscreen and intuitive menus to help artists input the correct kiln firing temperatures, as well as PID control algorithms to ensure maximum precision in the execution phase. Furthermore, all of the products in the TAP Ecosystem include integration with the TAP Kiln Control Mobile app – allowing for artists to remotely control and monitor their projects from their smartphone or tablet!

Explore Temperature Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries provide users 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 Control Mobile app, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

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:

Shop the most advanced programmable digital kiln controllers for sale.
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Kiln Firing Chart for Pottery and Ceramics [Infographic]

Kiln firing chart for ceramics and pottery

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.

A pottery kiln firing chart, with temperature labels for each cones as well as insights for what changes occur in the clay at various temperatures.

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:

CTA to shop pages for pottery kiln temperature controllers.

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

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:

Example of a 3-step kiln firing schedule in order to illustrate the format and various components of firing schedules

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:

A 3-step kiln firing profile plotted as a line graph

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:

A kiln firing schedule written in 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”.

A full fuse firing schedule for 90 COE glass

  1. 400°F/Hr to 1250°F – hold 30 minutes.
  2. 600°F/Hr to 1490°F – hold 10 minutes.
  3. AFAP°F/Hr to 900°F – hold 30 minutes.
  4. 150°F/Hr to 700°F – hold 0 minutes.
  5. 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:

A glass casting firing schedule for 90 COE glass

 

 

  1. 100°F/Hr to 200°F – hold 6 hours.
  2. 100°F/Hr to 1250°F – hold 2 hours.
  3. 600°F/Hr to 1525°F – hold 3 hours.
  4. AFAP °F/Hr to 1200°F – hold 4 hours.
  5. 50°F/Hr to 900°F – hold 6 hours.
  6. 12°F/Hr to 800°F – hold 1 minute.
  7. 20°F/Hr to 700°F – hold 1 minute.
  8. 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:

An annealing firing schedule for a glass kiln

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:

A pottery kiln firing schedule for candling clay

  1. 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:

A bisque firing schedule for Cone 04 ceramics

  1. 80°F/Hr to 250°F.
  2. 200°F/Hr to 1000°F.
  3. 100°F/Hr to 1100°F.
  4. 180°F/Hr to 1695°F.
  5. 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.

Glaze firing schedule for Cone 04 ceramics

  1. 150°F/Hr to 250°F.
  2. 400°F/Hr to 1695°F.
  3. 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:

A schedule for normalizing 1095 steel in a heat treat oven

  1. AFAP°F/Hr to 1600°F – hold for 15 minutes.
  2. 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:

Heat treat schedule for quench hardening 1095 steel

  1. AFAP°F/Hr to 1600°F – hold for 15 minutes.
  2. 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:

Tempering firing schedule for 1095 steel

  1. AFAP°F/Hr to 400°F – hold for 2 hours.
  2. 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:

Shop TAP Kiln Controllers CTA

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How to Use a Pottery Kiln Temperature Controller

Blog header image for 'How to Use a Pottery Kiln Temperature Controller.'

Pottery firing is the process of heating clay to transform raw clay into ceramic. Potters and ceramicists use pottery kiln temperature controllers to control the temperature of their kiln throughout the firing process to ensure that their pottery comes out hard, durable, and error free.

Before getting into the nitty gritty of how to operate a pottery kiln temperature controller, we’ll be exploring a general overview of the pottery firing process.

The 3 Stages of Pottery Firing

Regardless of the type of clay you’re using, pottery firing typically requires 3 basic steps.

Step 1: Drying

Raw clay is naturally moist. However, if you fire pottery before drying out the clay, then the water turns to steam, possibly resulting in fissures, cracks, or blow outs. Prior to pottery firing, it’s necessary to get the clay as dry as possible. This process is known as drying.

Some potters prefer to let their clay air dry, which typically take 24 to 48 hours depending on the thickness of the clay. However, there are ways to speed up the drying process, such as using a dehydrator, a desiccant chamber, or even using a hairdryer on low heat.

Even once the clay feels dry there is often still moisture trapped deep within the clay, so many potters do what’s known as candling or water smoking. Candling is when you heat your pottery in a kiln at low temperatures (typically around 122° F) for a prolonged period of time in order to eliminate moisture. When candling clay, it’s super important to keep your kiln below 212° F. Anything higher than that, and the water inside the clay boils, turns to steam, and can cause your pottery to explode – which is obviously no bueno!

A potter molding raw clay.
Raw clay is moist, moldable, and water soluble. However, it must be allowed to fully dry prior to pottery firing.

 

Step 2: Bisque Firing

Once the clay is mostly dry, it’s time to perform what’s known as a bisque firing. Bisque firing is when you fire the clay at a higher temperature to turn the clay into ceramic! During bisque firing, the clay vitrifies – or becomes glass-like. While raw clay is moist, moldable, and water-soluble, ‘bisqueware’ is hard, brittle, and won’t dissolve in water.

During a bisque fire, the properties of the clay change as the pottery is heated to increasingly higher temperatures:

  • At approximately 660° F, the clay becomes bisque. Water molecules that were chemically bonded to the clay are driven off. At this stage, the clay becomes fully dehydrated or ‘bone dry.’
  • At around 930° F, the clay becomes ceramic. This means that its chemical properties are permanently changed and it can no longer dissolve in water.
  • Between 1730° F and 1832° F, the clay becomes sintered. This means that the particles on the surface of the pottery are bonded together, increasing in hardness and density. However, the surface is still porous enough to accept glazes.

To avoid breakage, it’s important that the clay is slowly brought up to temperature and then allowed to cool slowly. A pottery kiln temperature controller allows potters to input the Setpoint (the temperature of the kiln) and the Ramp Rate (how quickly the kiln is heated up)to ensure that the pottery firing is successful.

Step 3: Glaze Firing

Once the bisqueware is fully cooled, potters and ceramicists apply glazes to the outside of the pottery to add color, change texture and finish, or to make the pottery water resistant or waterproof. Often, several layers are needed.

Once glaze has been applied and allowed to fully dry, the pottery is fired a second time. This is known as glaze firing. Glaze firing is typically done at the same temperature as the bisque firing, or slightly lower. Glaze firing at a higher temperature than the bisque firing can result in defects, blisters, bubbles, a cloudy finish, or other imperfections in the glaze.

The Role of a Pottery Kiln Temperature Controller

A pottery kiln temperature controller is the device that is used to manage the temperature of the kiln during a pottery firing. For electric kilns, automatic kiln controllers allow potters and ceramicists to preprogram their kiln to reach specific temperatures at specific time intervals.

Using Pottery Kiln Temperature Controllers to Create a Firing Schedule

The most advanced pottery kiln temperature controllers – such as the TAP and TAP II Controllers by SDS Industries – use an intuitive touchscreen interface to allow users to create the schedule for their pottery firings.

A schedule is a list of steps for each stage of the firing schedule. Each step includes:

  • Step #: The order in which the steps of the schedule occur.
  • Ramp Rate: The speed at which the kiln is heated or cooled (typically measured in degrees per hour).
  • Setpoint: The maximum temperature the kiln reaches during this step.
  • Hold Time: The length of time the kiln stays at temperature.

You can check out various sample schedules for firing ceramics here, courtesy of the Ceramic Arts Network. However, it’s important to follow the setpoint instruction for the type of clay you’re using, as well as the specific glaze. Pottery firing schedules aren’t one-size fits all!

Pottery kiln temperature controllers allow potters and ceramicists to create, name, and save different firing schedules for candling, bisque firing, and glaze firing. These can be easily edited to create specific schedules for different types of clays and glazes.

Pottery Firing with a Pottery Kiln Temperature Controller

Once the schedule has been created, the artist simply loads their piece into the kiln and presses ‘Start.’ At this point, the pottery kiln temperature controller automatically takes care of the rest, ensuring that the pottery is fired at the correct temperature from beginning to end.

However, for additional peace of mind, potters can use their pottery kiln temperature controller to set alerts or alarms to let them know when the kiln has reached specific stages in the firing process.

Using a Mobile App to Monitor and Control Your Pottery Firing

Additionally, today, potters and ceramicists have the option to monitor and control their pottery firing schedule from the convenience of their smartphone or tablet.

The TAP Kiln Control Mobile App, available on iOS and Android, integrates with pottery kiln temperature controllers to let potters:

  • Monitor their kiln remotely with real-time updates.
  • Skip firing steps or abort firings.
  • Receive real-time firing updates.
  • Create and modify schedules.
  • View firing logs with by the minute data points.
  • Update kiln settings.
  • And more!

By upgrading to a premium subscription, TAP Kiln Control Mobile App users unlock additional convenience and quality-of-life features like Remote Start!

What is a PID Control Algorithm?

When firing pottery, temperature precision plays an important role in ensuring consistent outcomes. Pottery kiln temperature controllers that utilize a PID, or “Proportional Integral Derivative,” control algorithm, detect and compensate for discrepancies between input temperature and the temperature of the kiln. Basically, this means that PID controllers are extremely precise in reaching (and maintaining) specific temperatures during the firing process, minimizing the possibility of errors.

TAP Digital Kiln Controllers and Standalones utilize PID control algorithms, along with high quality components and preventative maintenance alerts, to ensure that potters and ceramicists can focus on their craft, without having to worry about the performance of their kiln.

Learn More About the Most Advanced Pottery Kiln Temperature Controllers

For pottery firing, the TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use 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.

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

CTA to shop pages for pottery kiln temperature controllers.