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When to Use a Single Setpoint Controller

Single setpoint controllers are used for metal heat treat and executing simple kiln firing schedules.

When shopping for a kiln controller, it’s important to get a controller with the functionality you need. While advanced programmable digital kiln controllers have robust features to easily execute even the most complex firing schedules, some kiln operators don’t need to execute complex schedules with specific ramp rates for multiple steps. For these operators, a single setpoint controller might be a more affordable option.

Types of Artists a Single Setpoint Controller Won’t Work For

Before discussing the types of artists who should consider purchasing a single setpoint controller, it’s important to discuss the types of artists a single setpoint controller won’t work for. After all, buying a kiln controller that doesn’t include the functionality you need is a total waste of money!

Most Glass Artists

For most glass artists, a single setpoint controller won’t be a viable kiln control option. Kiln firing schedules for glass require the kiln to heat up to multiple setpoints at highly controlled ramp rates. If you heat up glass too fast or cool it down too quickly it can cause breaking or jeopardize its structural integrity.

While glassblowers can use a single setpoint controller to control their pick-up ovens, most glass kilns require advanced process controllers.

Most Ceramic Artists

Likewise, most ceramic artists will probably need to invest in a multi-setpoint kiln controller. Like with glass, most firing schedules for ceramic require multiple steps with specific ramp rates to avoid blowouts and preserve the structural integrity of the ceramic piece. It is worth noting that throughout most of kiln history, pottery was fired without the use of a multi-setpoint controller (or any controller at all!). But for most modern ceramic artists, an advanced multi-setpoint controller will be a better option.

However, if a ceramic artist uses a dedicated kiln for candling clay, a single setpoint can be a good control option for that application.

Artists Who Want Maximum Convenience

Additionally, a single setpoint controller does require more manual intervention. It’s up to the user to manually turn the kiln off or enter a new setpoint for an additional step. The soon-to-be released TAP&Go Single Setpoint Controller allows user to abort firings from their smartphone via TAP Kiln Control Mobile. However, many artists appreciate the convenience of having their controller automatically terminate firings once the necessary hold time has been reached. For kiln operators who want the convenience of having their controller automatically manage the entire firing schedule, a multi-setpoint controller will be a better option.

Types of Artists Who Should Consider a Single Setpoint Controller

Now that we’ve covered the types of artists a single setpoint controller won’t be a good fit for, let’s discuss those who should consider a single setpoint controller. Afterall, it doesn’t make sense to pay for functionality you don’t need!

Heat Treat Artists

For heat treat artists, such as those who make blades, jewelry, or work with metal clays, most firing schedules only require a single setpoint. In heat treat, ramp rates only apply to the cooldown process. These largely occur outside of a kiln through quenching, exposing the metal to room temperature, or insulating the metal in blankets or sand.

Single setpoint kiln controllers can be the perfect solution for bladesmiths, such as Delight Valley Blades.

For these types of artists, a single setpoint controller is the perfect solution! Additionally, a single setpoint controller can be used for the following applications:

  • Storing material at a single, controlled temperature.
  • Heating material to ensure it stays dry.
  • Controlling the temperature of a greenhouse or hydroponic tank.
  • Candling clay prior to firing.
  • Brewing beer (although a multi-step controller can add significant convenience!).

The TAP&Go Single Setpoint Controller by SDS Industries

If a single setpoint controller sounds like a good solution for your kiln control needs, we encourage you to check out the soon-to-be released TAP&Go Single Setpoint Controller! Designed specifically for heat treat artists, knifemakers, or users who don’t need to execute complex firings, TAP&Go takes the precision and ease-of-use of TAP and simplifies it into the most advanced single setpoint controller on the market.

TAP&Go is an advanced single setpoint kiln controller by SDS Industries.

With TAP&Go, heat treats artists have the ability to:

  • Easily enter the temperature you want the kiln or oven to heat to – from the 2.4” touchscreen or the TAP Kiln Control Mobile app – and let the controller do the work.
  • Enjoy complete remote monitoring and control through the TAP Kiln Control Mobile app with a premium subscription.
  • Use TAP&Go’s built-in WiFi and Bluetooth to automatically pair with the TAP Kiln Control Mobile app.
  • Prevent eye strain with light and dark modes and large, full-text displays.

 

Explore Single Setpoint and Multi-Setpoint Controllers by SDS Industries

Whether you’re looking for a single setpoint or multi-setpoint controller, TAP has you covered! The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use multi-setpoint 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.

The soon-to-be-released TAP&Go includes many of the benefits of TAP but streamlines everything into a single setpoint controller so that heat treat artists only have to pay for the functionality they need!

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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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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What Is a Pyrometer? Understanding Pyrometers for Kilns

What is a pyrometer? A pyrometer is a temperature monitoring device for high temperature applications.

What is a pyrometer? A pyrometer is a device that measures high temperatures for applications beyond the range of a mercury thermometer (673° F or 356° C). Pyrometers, also referred to as pyrometric devices, are used to monitor temperature for a wide variety of applications. From kilns, furnaces, heat treat ovens, and industrial processes, to measuring the surface temperatures of distant planets!

Contact vs Non-Contact Pyrometers

Pyrometers can be contact or non-contact. Contact pyrometers, such as pyrometers for kilns, use thermocouples that are in thermal contact with the object or atmosphere. Non-contact pyrometers, on the other hand, use optical systems to measure the radiation of a surface without the need for thermal contact.

Both types of pyrometers have their pros and cons. Contact pyrometers, also known as resistance pyrometers or thermocouple pyrometers, are subject to degradation from heat exposure and are limited by the range of the thermocouple. However, they are highly accurate and usually less expensive.

Non-contact pyrometers, also referred to as optical pyrometers, radiation pyrometers, or infrared pyrometers, have far greater range – both in terms of physical distance as well as maximum temperature. Non-contact pyrometers can measure temperatures exceeding 7232° F or 4000°C – nearly three times higher than most contact pyrometers. Non-contact pyrometers can also measure temperatures of moving objects or objects that cannot be touched. However, they are significantly more expensive and less accurate.

Pyrometers for Kilns

As you can probably imagine from the comparison above, contact pyrometers are generally more suitable for kiln temperature monitoring. Affordability and accuracy, as well as the temperature range of most kiln firing schedules, makes using a thermocouple pyrometer with your kiln a pretty obvious choice!

A Brief History of Pyrometers for Kilns

While the earliest known pyrometer dates back to the “Hindley Pyrometer” in 1732, the first pyrometer for kilns was invented by English potter Josiah Wedgwood in the 1780s. Josiah Wedgwood is an interesting figure in the history of pottery. He was a wildly successful potter, industrialist, and entrepreneur – a savvy marketeer, technological innovator, prominent abolitionist, and fashion tastemaker in 18th century England, possibly the closest thing pottery has had to a ‘rockstar.’

(An interesting aside, the fortune Wedgewood amassed selling his line of pottery to the aristocracy of England and the rest of Europe, including Queen Charlotte of England and Queen Catherine of Russia, helped fund the research of his grandson, Charles Darwin. Yes, that Charles Darwin. Wedgwood was quoted as saying, “Fashion is infinitely superior to merit,” although his pottery was widely considered to possess both due to his dedication to utilizing the latest advancements in technology).

Wedgwood’s pyrometer was an optical pyrometer that was used to visibly compare the color of the clay in the kiln to the color of clay fired at known temperatures (similar in principle to this firing chart!). Later he replaced this early pyrometric technology with using of shrinking clay rings or expanding metal bars to measure the temperature of his kilns.

In 1885, Dr. Herrmann Seger developed the pyrometric cone, another pyrometric device based around a similar principle, which remained the standard in pyrometry for at home kilns all the way up until the invention of digital kiln controllers and digital pyrometers in the 1980s. For industrial kilns and furnaces, the Siemens brothers developed a platinum thermometer that could measure temperatures up to 1832° F or 1000° C in the 1860s through the 1870s.

Alternatively, for higher temperatures, the disappearing filament pyrometer was invented by L. Holborn and F. Kurlbaum in 1901. This was another optical pyrometric device that worked by adjusting current through a filament until it matched the color (and thus temperature) of an incandescent object. Evolutions in disappearing filament and brightness pyrometers continued throughout the 20th century.

Modern Digital Pyrometers for Kilns

In the 1980s, the world became digital, and the modern thermocouple pyrometer was born. Digital pyrometers for kilns use thermocouples that attach to a temperature sensor to precisely monitor kiln temperature.

While digital kiln controllers can be used to monitor kiln temperature, a dedicated digital pyrometer adds additional capabilities. For instance, you can use a digital pyrometer to add digital temperature monitoring to a manual kiln or use it in addition to a programmable digital kiln controller to act as a safety redundancy device to provide automatic safety shutoff in case of relay failure.

TAP Monitor is an advanced digital pyrometer that brings precise temperature measuring and remote monitoring to any kiln or heat treat oven.
TAP Monitor is an advanced digital pyrometer that brings precise temperature measuring, remote monitoring, and safety redundancy to any manual or automatic kiln or heat treat oven.

The TAP Monitor Digital Pyrometer Limit Controller

The latest evolution in digital pyrometers for kilns is the TAP Monitor, which is now available for preorder! The TAP Monitor is an advanced, user-friendly limit controller and digital pyrometer that gives kiln operators the ability to precisely monitor kiln temperature – remotely! – regardless of their existing kiln control method.

Available as a plug-and-play standalone pyrometer limit controller or as a set of configurable components for DIY installs and oven builds, TAP Monitor gives ceramicists, potters, glass artists, and bladesmiths the ability to:

  • Precisely monitor the temperature of their kiln, oven, or forge via the TAP Kiln Control Mobile App.
  • View digital pyrometric readouts from any manually controlled kiln, including remote readouts via TAP Kiln Control Mobile when TAP Monitor is connected to a local network with internet access.
  • Easily add precise, real-time digital temperature readings to their manual kiln or oven.
  • Pair TAP Monitor with their existing automatically controlled kiln for remote monitoring.
  • For added safety, use TAP Monitor as a standalone and safety relay controller. 

Explore Kiln Control Solutions by SDS Industries

In addition to the TAP Monitor Digital Pyrometer, the TAP Ecosystem includes a variety of programmable kiln controllers that give artists complete control of their kilns – without complicated controls or clumsy user interfaces. The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use programmable digital kiln 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, pyrometers, 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 Monitor Digital Pyrometer for kilns

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How Much Do Kilns Cost? The True Costs of Owning a Kiln

Description of kiln costs - from purchase and shipping to installation, operation, and maintenance.

For most artists, purchasing a kiln is a pretty big investment. Newer artists, especially, will probably have a lot of questions about what they’re getting into! How much do kilns cost? What about installation and kiln maintenance? Are kilns safe? What type of kiln is right for me? What kind of controller should I use for my kiln?

Don’t worry, we’ve got you covered! You can find our guides on kiln maintenance, kiln safety, types of kilns, and kiln control methods below. And by the end of this article, you’ll have a complete understanding of kiln costs!

Note: For the sake of this article, we’ll be primarily focusing on kiln costs for electric kilns, which are the most common kilns for the hobby kiln and studio kiln market. Gas kilns are typically more expensive, ranging from $3,000 on the extreme low-end to $30,000+ for a high-capacity gas kiln and have their own unique operating and installation costs.

Understanding Kiln Costs

When people think about kiln costs, a lot of the time they only think about the upfront cost of purchasing their kilns. While we’ll be covering purchase costs in depth, there are additional costs to consider. These include installation costs, kiln maintenance costs, material costs, as well as firing costs.

For the hobbyist, understanding these costs will help avoid unforeseen expenses. It will also help determine the most suitable type of kiln and possibly save some money! But for the professional artist, accurately tracking kilns costs can help make sure they’re pricing their wares correctly.

The Cost of Buying a Kiln

For most artists, purchasing a kiln is by far the most expensive part of kiln ownership. Kiln costs vary tremendously, ranging from around $700 for compact kilns to $20,000+ for large, higher powered, industrial grade kilns. There is also a robust used kiln market on Craigslist, eBay, Facebook Marketplace, and other online markets, where pre-owned kilns range from $275 to $3,000+ dollars.

Factors that influence kiln costs include:

  • Size: Generally speaking, the bigger the kiln, the more expensive – both at the time of purchase and in terms of potential installation, maintenance, and power costs.
  • Power Rating: Larger kilns and hotter kilns typically require more power and are generally more expensive.
  • Maximum Temperature: Generally, kilns with a higher maximum temperature are more expensive than comparable kilns with lower maximum temperatures.
  • Materials Fired: Glass kilns, ceramic kilns, knife kilns, and metal clay kilns (for jewelry) have different price ranges (which we’ll be covering more in-depth below).
  • Temperature Controller Method: The type of kiln controller that comes included with your kiln will impact its price by up to several hundred dollars – but your controller will have a major impact on your kiln firing experience and the functionality of your kiln.
  • Shipping Costs: As a larger item, shipping costs for kilns can add a substantial amount to your purchase price. When comparing prices between kiln suppliers, check to see whether shipping costs are included with the purchase of your kiln.

Whew, that may seem like a lot of factors to keep in mind! Don’t worry, we’ll be covering each of these considerations more in-depth. To help narrow your focus when purchasing a new kiln, it’s important to ask yourself the following questions:

  • How will I be using my kiln? What types of kiln firing schedules will I need to be able to execute?
  • Based on the media and techniques I use, what kiln firing temperatures and element placement will I need for my projects?
  • How big does my kiln need to be? How much space do I have to install the kiln at my home or studio?

The more specifically you can answer those types of questions, the easier it will be to determine which features you need to shop for and the kiln costs you should budget for.

Kiln Size Price Ranges

When it comes to buying a kiln, how big does your kiln need to be? Well, that depends…how big are the projects you’ll be firing? If you only need your kiln for slumping glass or firing jewelry or other small objects, chances are you’ll be able to save a lot of money on upfront costs and installation by purchasing a compact kiln.

However, if you’re firing large ceramic pieces – or firing multiple projects at a time – you’ll probably need to spring for a larger kiln.

Below are the average and median prices for kilns based on size (kiln prices throughout this article are based on aggregate price data from Kiln Frog).*

  • Compact Kilns: Under 15”
    • Price Range: $924.00 – $3318.54
    • Average Price: $1594.83
    • Median Price: $1474.16
  • Medium Kilns: 13” – 18”
    • Price Range: $916.00 – $4623.86
    • Average Price: $2028.56
    • Median Price: $1921.81
  • Large Kilns: 17” – 24”
    • Price Range: $1558.00 – $6889.54
    • Average Price: $3240.21
    • Median Price: $3139.00
  • X-Large Kilns: Over 24”
    • Price Range: $2416.00 – $25328.55
    • Average Price: $6669.63
    • Median Price: $4582.80

As you can see, the size of the kiln makes a big difference in price!

*Price data in this article includes current promotions – prices may vary.

Kiln Costs Based on Power Rating

Another factor that can influence kiln costs – for purchase, installation, and your electric bill – is the power rating of your kiln. When it comes to power rating, there are three ratings you need to understand: voltage, amperage, and wattage.

Voltage is the electric potential of a circuit. Comparing electricity to plumbing, voltage could be considered the pressure in a pipe. In the U.S., kilns typically come in two different voltage configurations: 120V and 240V, which correspond with the electric grid. 120V kilns are typically less expensive and match the voltage of a standard residential wall outlet; however, kilns exceeding 15 amps will need to be installed on a dedicated circuit.

A 240V kiln, on the other hand, needs a special wall outlet (other large appliances, such as wall ovens, AC units, and dryers use 240V outlets). Chances are, you will need the help of an electrician to run a new outlet in order to install your kiln. According to HomeGuide, this will cost anywhere from $250 – $800.

Amperage is the units of electrical current in a circuit. Extending the plumbing analogy, current is similar to the capacity of a pipe: the wider the pipe, the more water that flows. Kilns range from 13 amps to 80 amps. 120V kilns typically only go up to 30 amps, while 240V kilns can range anywhere from 30 amps to 80. At 48 amps or higher, a kiln will have to be wired directly into your power supply – another additional expense!

Watts measure the rate of power flow, calculated by multiplying voltage by amperage. Smaller 120V kilns typically draw between 1500 and 1800 watts, while a large 240V kiln can draw up to 11000 watts. TAP Kiln Controllers by SDS Industries allow you to enter your kiln’s watt rating, as well as the cost per kilowatt hour from your electric bill to automatically calculate your cost per firing.

The kiln costs tracking feature on TAP Kiln Controllers allows artists to automatically track how much they spend per fire.
The TAP Kiln Controller by SDS Industries allows artists to easily track their cost per fire on their electric kiln.

Kiln Costs by Maximum Temperature

Different kilns are capable of reaching different maximum temperatures. Generally, the hotter the kiln, the higher the kiln costs! If you need to fire Cone 14 porcelain, expect to spend more money than if you only need to fire Cone 06 ceramics. Reviewing these firing schedules for glass, ceramic, and metal heat treat can help you figure out which temperatures you’ll need your kiln to be able to reach based on the media and techniques you use.

Kiln Costs by Materials Fired

Speaking of media, when shopping for a new kiln, you’ll find that there are different kilns designed specifically for glass, ceramics, metal heat treat (for objects such as blades and knives), and metal clay (for jewelry and small metal trinkets). How do the materials you fire impact kiln costs?

Kilns have different dimensions and maximum temperatures based on the materials they’re designed to fire. Generally, metal clay kilns will be smaller than glass kilns, which will be smaller than knife kilns. Ceramic kilns tend to be larger and cylindrical, since you can stack pottery during fire. You can expect the price of the kiln to scale accordingly.

Additionally, ceramic kilns and heat treat kilns will typically need to be capable of reaching higher temperatures than metal clay kilns or glass kilns.

Broadly speaking, metal clay kilns will be the least expensive, and ceramic kilns will be the most expensive. Glass kilns and metal heat treat ovens often fall somewhere in between.

Temperature Controller Costs

Finally, an extremely important consideration when buying a kiln is deciding which brand and model of kiln controller to purchase with your kiln. After all, the kiln controller will be your primary interface with your kiln and will largely determine your user experience. Your kiln control method will determine the accuracy of your kiln firing, as well as what you can program the kiln to do.

Upgrading to a fully featured touchscreen programmable digital kiln controller will add a few hundred dollars to your kiln costs compared to a rudimentary 3-key model. Is it worth it?

In our opinion, yes. Definitively. An advanced, easy-to-use kiln controller like the TAP Kiln Controller gives you the ability to:

  • Easily navigate your controller and manage your firing schedules with just a few finger presses.
  • Name, save, and edit unlimited firing schedules with an unlimited number of steps per schedule.
  • Easily find and select the right schedule with alpha-numeric, full text displays.
  • Integrate your controller with the TAP Kiln Control Mobile App so that you can remotely monitor your kiln and create, modify, and execute firing schedules from your mobile device.
  • Enjoy peace-of-mind with push notification alerts and alarms to keep you informed of your firing status, notify you when it’s time for preventative maintenance, or let you know when unexpected conditions occur.

Additionally, SDS Industries is working on a lineup of more cost-accessible controller options that contain many of the advanced functions of TAP at a lower price point, with all kiln controller inputs performed via your smartphone.

Read our side-by-side kiln controller manufacturer comparison to compare the features of TAP against what you get with lower-priced controller options.

Additional Kiln Costs

In addition to kiln costs at point of purchase and installation, there are also longer-term costs to keep in mind.

We mentioned installation costs earlier. You should plan on budgeting up to $800 if you will need the help of an electrician in installing your kiln. Additionally, if you’re purchasing a ceramic kiln, you may need to buy and install a ventilation system which can run another $200 to upwards of $800.

For kiln maintenance, you will have to replace thermocouples, elements, and mechanical relays at regular intervals. Depending on how frequently you use your kiln and the temperatures you fire to, you should plan on budgeting at least $100 to $200 dollars every year or two to replace these components.

And, finally, you will have to budget for materials. Material costs can vary greatly per artist, but you should plan accordingly!

Conclusion

There you have it! Hopefully, this article has given you a full understanding of the true cost of owning a kiln. However, you should look at kiln costs as a long-term investment. If you take care of your kiln, it could last you for decades and give you countless hours of enjoyment and self-expression – so it’s hard to put a price tag on that! But it’s also important to know what you’re getting into and budget accordingly.

Explore Programmable Digital Kiln Controllers by SDS Industries

If you’re buying a new kiln, you’ll want to make sure it’s coming with the right controller. Ask your kiln supplier about TAP! The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use programmable digital kiln 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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What is an Industrial Kiln? Understanding Commercial Kilns, Furnaces, and Ovens

Industrial kilns are typically much larger and more powerful, designed to process large quantities of materials in industrial settings.

Kilns aren’t just limited to home and studio applications. Industrial kilns, or commercial kilns, are used in a wide variety of industrial processes. From mass producing ceramic tableware to processing plastic, industrial kilns are used to create many of the objects you use in day-to-day life.

Compared to kilns for personal or artistic use, industrial kilns are typically much larger and more powerful, designed to process large quantities of materials in industrial settings. Designed for mass production and commercial use, industrial kilns are often permanently installed and capable of reaching extremely high temperatures.

Example of a front-loading commercial kiln.

Industries That Use Commercial Kilns

Industrial kilns, furnaces, and ovens are used across a wide variety of industrial sectors including:

  • Ceramic: Industrial kilns are used in the ceramic industry to produce tableware, pottery, tile, and other ceramic products.
  • Glass: Industrial glass kilns, furnaces, and annealers are used in the glass industry to produce windows, sheet glass, drinkware, bottles, mirrors, and more.
  • Construction and Building Materials Manufacturing: In the construction industry, commercial kilns and heat treat ovens are used to produce brick, tiles, windows, machinery, tools, and other building materials.
  • Metal Processing and Manufacturing: Industrial heat treat ovens and furnaces are used to process metal for a wide variety of applications including, but not limited to, knifemaking, jewelry production, and silverware manufacturing.
  • Plastic Processing and Manufacturing: The plastic processing and manufacturing industry uses commercial kilns to heat raw material into finished or semi-finished plastic products.
  • Food Industry: In the food industry, industrial kilns and commercial ovens are used to dry, cook, and process food.
  • Waste Management: The waste management industry uses commercial furnaces for incineration, recycling, and energy recovery.

However, these are just a few of the industries that use industrial kilns, furnaces, and ovens. Kilns and ovens are also used in the medical, pharmaceutical, electronic, automotive, military and defense, and aerospace industries (among countless others!).

Read more about the history of industrial kilns.

The Differences Between Industrial Kilns, Furnaces, and Ovens

When it comes to commercial thermal processing equipment, there are three main categories: kilns, furnaces, and ovens. Superficially, all these terms can be used interchangeably. However, typically, each of these terms is used to denote equipment used for specific use-cases or to describe equipment capable of reaching specific temperatures:

  • Industrial Kiln: More likely to be used to describe thermal processing units used to process ceramics or glass. Typically used to describe units that reach maximum temperatures of approximately 1400° C (2552° F).
  • Industrial Furnace: More likely to be used to describe thermal processing units used for metal heat treatment and metallurgy. Often used to describe units that reach peak temperatures exceeding 1400° C (2552° F), all the way up to 1750° C (3182° F).
  • Industrial Oven: More likely to be used to describe thermal processing units used for the food, electronic, medical, and pharmaceutical sectors. Often used to describe units whose processes don’t result in a fundamental phase change (such as drying, moisture reduction, and bakeout).

Industrial Kiln Controllers

Commercial kilns are “industrial grade,” which means they have more stringent requirements for kiln safety and input and output precision. Industrial kiln controllers, also known as ICS (Industrial Control Systems) kiln controllers, must be capable of executing a variety of complex firing schedules with extreme precision.

The TAP Kiln Controller is the most advanced industrial kiln controller, with precise input and output precision.

The TAP Kiln Controller by SDS Industries includes a variety of features and benefits for industrial kiln usage, such as:

  • PID (Proportional Integral Derivative) control algorithms to ensure maximum accuracy between temperature input and output.
  • Multizone temperature control to set specific temperatures in up to three different areas of an industrial kiln or oven.
  • The ability to create, store, edit and execute an infinite number of firing profiles.
  • The ability to remotely monitor commercial kilns and edit and execute firing processes through the TAP Kiln Control Mobile App.
  • Advanced diagnostics and preventative maintenance alerts to ensure peak performance for industrial thermal processes.
  • High quality components for maximum precision and durability.

Read more about the roles and functions of industrial kiln controllers.

Explore Industrial Kiln Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use industrial kiln 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 to allow you to easily manage and execute your kiln firing schedules.

We invite you to explore our selection of programmable industrial 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 industrial kiln controllers for sale

CTA: Choose the Most Advanced Industrial Kiln Controllers

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Thermocouples: Differences Between Thermocouple Types

Learn more about the physical properties and heat treating applications for different types of thermocouples.

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.

An example of a thermocouple for a kiln or heat treat oven.

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.

Diagram of the components and wiring schematics of thermocouples.

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:

Shop programmable 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:

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Guide to Choosing Heat Treating Controllers

Guide to Choosing a Heat Treating Controller Blog Header Image

When it comes to heat treatment, precision and stability are key. Heat treating controllers ensure that you’re able to precisely control the temperature of your oven or furnace throughout each stage of the heat treat process. 

Why is this important? Whether you’re making knives, swords, or industrial components, correct temperature and soak time determine whether your metalwork has the intended properties.

Definition of Heat Treatment

Before getting into the ins-and-outs of heat treating controllers, let’s define heat treatment and explore common types of heat treatments.

Heat treatment is a process of heating and cooling metals and alloys in a controlled manner to alter their physical and mechanical properties, such as hardness, ductility, malleability, temperature resistance, and material strength. Heat treatment has a wide range of applications and is used for everything from making knives or other simple tools to building aerospace components! 

Stages of Heat Treat

At an extremely high level, every type of heat treatment involves 3 main stages:

  • Heating: Heating the metal or alloy to a specific temperature, ensuring that it heats evenly.
  • Soaking (or Holding): Keeping the metal at temp for a specific period of time.
  • Cooling: Bringing the metal or alloy back to room temperature. 

Depending on the application and the desired properties of the metal, these stages may be repeated multiple times or may have specific requirements regarding Ramp Rate (how quickly the metal is brought to temp) or Cooling Rate (how quickly the metal is cooled to room temperature).

Common Methods of Heat Treatment

Below are common heat treating methods, as well as the effects they have on the metal:

  • Normalizing: The metal is heated to an extremely high temperature for a defined period of time and then air-cooled. Normalizing relieves internal stress and ensures uniformity, resulting in harder, stronger metals.
  • Annealing: The metal is heated beyond the upper critical temperature and then slowly cooled to soften it and increase its workability. Annealing increases ductility and toughness, while relieving stress, making the metal more resistant to fractures.
  • Hardening: The metal is heated until it forms an even solution and then allowed to cool to increase its hardness. 
  • Case Hardening: Only the outside of the metal is hardened, creating a durable outer layer while ensuring the metal retains flexibility and doesn’t become brittle.
  • Quench Hardening: After heating, the metal is cooled rapidly by dipping it into an oil, polymer, or water, resulting in very hard, very brittle metal.
  • Tempering: After hardening, the metal is heated to a lower temperature to reduce excessive hardness and relieve internal stress. Tempering makes metals less brittle.

What to Look for in a Heat Treating Controller

Regardless of the application, when choosing a heat treating controller it’s important to look for 3 main features:

  • Precision: Since temperature dictates the properties of the metal, it’s important to select a heat treating controller that precisely controls the temperature of your kiln or oven. PID (Proportional Integral-Derivative) controllers, such as the TAP Digital Controllers from SDS Industries, will result in the highest degree of precision, making them ideal for heat treatment.
  • Reliability: Consistency and stability are important considerations when buying a heat treating controller. High quality components, onboard diagnostics to verify input/output, energy-efficient design, and preventative maintenance alerts ensure reliability and consistent results.
  • Ease-of-Use: In 2023, heat treating controllers should make life easy for metalworkers, whether you do your heat treatments at home or in an industrial setting. The best digital controllers include touchscreen controls, mobile app integration, alerts, alarms, and the ability to create, name, and save unlimited schedules.
TAP II Heat Treating Controller
The TAP II Controller by SDS Industries is the most advanced, easy-to-use heat treating controller on the market today.


Single Setpoint vs Multi-Setpoint

Another consideration is whether you should purchase a Single Setpoint or a Multi-Setpoint controller. A Single Setpoint controller allows you to set your oven to a single temperature for an indefinite amount of time. For heat treatments that don’t require specific Ramp Rates, Single Setpoint controllers are often a more affordable option.

However, some heat treatments require specific Ramp Rates and multiple Setpoints, in which case you should choose a Multi-Setpoint controller. The TAP II Controller, which is the most advanced heat treating controller on the market, allows metal workers to create an unlimited number of Setpoints and Ramp Rates and save an unlimited number of schedules, making it ideal for complex heat treatments. (It’s also worth noting that Multi-Setpoint controllers are capable of Single Setpoint applications).

Coming Soon: TAP & Go

We at SDS Industries are excited to announce the TAP & Go Kiln Controller. Our most simplified control option yet, the TAP & Go is a Single Setpoint controller, making it ideal for heat treat, knife-making, or for users who don’t need to execute complex firings.

TAP & Go is built on a modular platform that will allow users to purchase add-ons like a 2.4” Capacitive Touchscreen, and Output Adapter, or an Input Power Adapter that snap right onto the Controller Board! TAP & Go is controlled almost entirely through the TAP Kiln Control Mobile App, making it a convenient and affordable heat treating controller.

With development and testing well underway, the TAP & Go is on track for release in the coming months. Make sure to subscribe to SDS Industries to learn more!

Choose the Heat Treating Controller That’s Right For You

If you’re in the market for a heat treating controller, the TAP and TAP II Controllers by SDS Industries are the most advanced, precise, and easy-to-use controllers on the market today. We invite you to explore our selection of digital controllers, standalones, and conversion kits on our online store. Or you can purchase TAP Digital Controllers or TAP-Controlled Heat Treat ovens through one of the following distributors:

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