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Heat Treat 101: Guide to Heat Treating

Guide for explaining heat treat processes, use-cases, and supplies

Let’s talk heat treat! Whether you’re crafting knives, blades, jewelry, tools, industrial components, or any other metal object, you’ll want those objects to have specific qualities – whether that’s shape, hardness, toughness, flexibility, or even electrical conductivity.

That’s where temperature comes into play.

Heat Treat Definition

Heat treat is the process of exposing metal or alloys to specific temperatures to change its molecular structure, which in turn alters its physical (and sometimes chemical) properties. Through controlled heating and cooling, heat treat can alter a metal’s hardness, ductility, malleability, temperature resistance, corrosion resistance, and material strength.

What Is Heat Treat Used For?

As you can imagine, heat treat has a wide range of applications – both artistic and industrial.

Artistic Use

Artists use heat treat to create knives, blades, jewelry, or ornamentation – basically any art or craft that involves metal. Heat treat artists use a series of specific firing schedules, along with cooling techniques, to shape metal and imbue it with the desired qualities, textures, and mechanical properties they want for their finished piece. These qualities may be decorative, functional, or both.

Single setpoint kiln controllers can be the perfect solution for bladesmiths, such as Delight Valley Blades.
Knife makers like Brock from Delight Valley Blades use heat treat to craft high quality blades that are both artistic and functional.

 

Industrial Use

In industrial processes, heat treat is an integral part of most manufacturing processes involving metal. Industries that rely on heat treat include medical, automotive, and electronic manufacturing.

Manufacturing processes that commonly involve heat treat include:

  • Machining: Creating the desired shape, size, or finish.
  • Joining: Connecting multiple objects into a unified structure.
  • Casting: Pouring liquid metal into a mold and allowing it to harden into a single object.
  • Shaping: Shaping raw metal into a specific shape or structure.
  • Molding: Pouring or pressing liquid or semi-liquid metal inside a mold.
  • Assembly: Connecting, fitting, and joining various components into a finished object.
  • Finishing: Making final adjustments to the finished object to make sure it fits the final design requirements.

Types of Heat Treat Processes

Different heat treat processes are used to alter the specific qualities of the metal or alloy. Often, different processes are used subsequently on a single piece. Below are common heat treating processes, as well as the effects they have on the metal:

  • Normalizing: The metal is heated to an extremely high temperature for a defined time period 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 alloy 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.

Stages of Heat Treat

Each heat treat process typically occurs in 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 and 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).

Heat Treat Schedules

Each type of metal has specific setpoints and hold times for each heat treat process. However, unlike other kiln fired mediums, ramp rates for heat treat mostly become a factor during cooldown – and largely occur outside of the kiln! As such, most heat treat firing schedules are single setpoint – and only include a single step.

Below is an example of a normalizing schedule for 1095 steel, which relieves internal stress and ensures uniformity, resulting in harder, stronger metals:

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.

As you can see, this heat treat schedule is extremely simplistic. You can find additional schedules for quench hardening and tempering 1095 steel in our article Understanding Kiln Firing Schedules for Glass Ceramics, Pottery, and Heat Treat.

Heat Treat Controllers

A heat treating controller is a device that uses your inputs to automatically manage the temperature of your heat treat oven. Heat treat controllers can be fully featured multi-setpoint controllers. But since heat treating schedules are typically single setpoint, a single setpoint controller like TAP&Go by SDS Industries may be a more economical solution.

The TAP&Go is SDS Industries' new, soon-to-be-released single setpoint controller designed specifically for heat treat.
The TAP&Go is SDS Industries’ new, soon-to-be-released single setpoint controller designed specifically for heat treat.

Regardless of whether you choose to go with a multi-setpoint or single setpoint controller, TAP Controllers by SDS Industries offer heat treat artists a ton of benefits, such as:

  • Work more efficiently and increase peace of mind with remote kiln control, kiln temperature monitoring, and real-time push notifications through TAP Kiln Control Mobile.
  • Improve consistency and save time by being able to save and access all of your different firing schedules for different processes and materials – without having to find the schedule you want in your firing notebook.
  • Enjoy intuitive menus and responsive touchscreen controls that make entering the correct schedule faster, easier, and more accurate than other heat treat controllers on the market.
  • Ensure maximum consistency with PID control algorithms and advanced diagnostics and preventative maintenance alerts.

Heat Treat Ovens

In addition to making sure you have the right heat treat controller, you’ll also need a heat treat oven, furnace, or knife kiln that’s capable of firing your medium of choice. When shopping for heat treat ovens, a couple factors to consider include:

  • Chamber Size: You’ll need a heat treat oven that has adequate chamber size to accommodate your medium. For instance, to heat treat blades, you’ll need a long, narrow chamber. But if you’re heat treating silver clay to make jewelry or trinkets, you may only need a small chamber.
  • Power Rating: Heat treat ovens with a higher power rating are typically capable of reaching hotter temperatures, which may be required for some metals or alloys. However, these ovens are more expensive (both for purchase and for operation) and may require installing a dedicated circuit or the installation of a special wall outlet.
  • Maximum Temperature: You’ll need an oven that’s capable of reaching the temperatures required for the metals and alloys you use.
  • Overall Dimensions & Configuration: Your kiln will have to be able to fit into your workspace or studio.
  • Durability, Reliability, & Support: A heat treat oven is a big investment. Manufacturers like Evenheat, Hot Shot Oven & Kiln, and Jen-Ken Kilns are American-made brands that have longstanding reputations for innovation, reliability, and customer service – plus, all of these manufacturers include TAP as a preinstalled option!
The Hot Shot 18K Pro Heat Treat Oven is designed for knife making, with an elongated chamber, patented cool-to-touch technology, and an integrated TAP Controller.
The Hot Shot 18K Pro is designed for knife making, with an elongated chamber, patented cool-to-touch technology, and an integrated TAP Controller.

Heat Treat Supplies

Finally, once you have your heat treat oven and controller, you’ll need supplies! For heat treat artists, the type of metals and allows you need largely depends on application. For example, silver clay is soft and pliable, making it a popular material for making jewelry and small trinkets. For bladesmithing, a wide range of metals and alloys may be used. For example, 1095 steel is easy to machine, easy to sharpen, and can hold a very sharp blade, making it a popular alloy in the knifemaking community. But it’s not stainless, and will be subject to corrosion, which means it won’t be ideal for kitchen cutlery. One of the most reputable suppliers for steel alloys for artists in the heat treat industry is New Jersey Steel Barron – if you’re looking for steel for your next knife making or bladesmithing project, they’re a great place to start!

Explore TAP Heat Treat Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use heat treat oven 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 heat treating oven controllers by SDS Industries

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Remote Kiln Control: How Do I Get Remote Start for My Kiln?

TAP Kiln Control Mobile provides artists with remote kiln control and remote start.

When we launched the TAP Kiln Control Mobile app in 2016, our vision was to give kiln operators and heat treat artists the same level of convenience and connectivity they enjoyed in all other areas of their lives. Responsive, easy-to-use touchscreen controls weren’t enough. We wanted to offer true remote kiln control, so artists could enjoy the flexibility of being able to remotely monitor their kilns and edit and execute their kiln firing schedules in real-time from their smartphone or tablet.

Developing TAP Kiln Control Mobile was a huge investment on our end. We had never developed a mobile app before, and we definitely dealt with speed bumps and learning curves along the way. But through our commitment to supporting the artists in the TAP community, and through their helpful feedback, we’ve continued to launch software updates to continually improve TAP Kiln Control Mobile.

Today, it’s – by far (as far as we know!) – the highest rated kiln control mobile app, and the only one that offers true remote kiln control.

 

What Is Remote Start? And Why Does It Matter?

In 2023, we released Remote Start – one of our all-time most requested features. With Remote Start, TAP Artists can turn on their kiln and initiate a kiln firing schedule no matter where they were. This feature – combined with the ability to remotely edit schedules, make real-time firing adjustments, skip steps, and abort firings – finally gave artists true remote kiln control for the first time ever.

This represented a huge step forward for convenience and flexibility for all artists – but it also represented a major advancement in accessibility for artists who may have physical disabilities. With TAP Kiln Control Mobile, artists don’t have to be able to walk over to their bend over in front of their controller to program their kiln

For safety reasons, you should never leave your kiln unattended. But that doesn’t mean you should have to be physically right beside your kiln for the entire duration of the kiln firing process. In real life, sometimes you need to be able to step away from your kiln. Remote Start, along with the other features of TAP Kiln Control Mobile, gives artists the flexibility of being able to multi-task and gives them the peace of mind of always knowing the status of their kilns.

This is a stark contrast from using other kiln controllers. When SDS Industries’ VP & Chief Creative Officer, Brittany Gabel, was a glass art student at Rochester Institute of Technology, she would have casting projects that required multiple days’ worth of firings. She would have to go back to campus at odd hours throughout the night or very early mornings to check on the kiln to make sure her projects were firing successfully. She would have to assess what step the firing process was at, or sometimes wait around until the kiln reached a certain step so that she could add more glass to her mold. Sometimes she’d miss her window entirely.

With remote kiln control through TAP Kiln Control Mobile, she would have been able to know exactly when she needed to attend to her kiln, saving her tons of time and effort.

Why Is Remote Start Only Available with a Premium Subscription?

For all of the different controllers in the TAP Ecosystem, Remote Start is only available with a Premium Subscription to TAP Kiln Control Mobile, which is available for $4.99 a month or $49.99 a year. While some customers are frustrated by the prospect of having to pay a subscription for an app when they already made a significant investment in the kiln, 100% of the net subscription fees for the Premium Plan goes directly back into the app for maintaining our servers, developing new features, and providing improvements for all users.

If we could give away all the premium features for free, we totally would! But unfortunately, that just isn’t feasible. However, while features like Remote Start are super convenient, they are also 100% optional and don’t affect the core functionality of your TAP Controller.

How to Get Remote Start for Your TAP Controller

As we mentioned earlier, Remote Start is a premium feature that is only available on a Premium Plan for the TAP Kiln Control Mobile app. First, you will need an active Premium Plan for the TAP Kiln Control Mobile app, as well as for your controller to be connected to WiFi.

A walkthrough of how to use the remote start function of TAP Kiln Control Mobile

Once these two conditions are met, all you have to do to activate Remote Start is to follow these steps:

  1. Select your kiln from the My Kilns screen of the TAP Kiln Control Mobile app.
  2. Click the Schedules tab at the bottom of the app.
  3. Press the blue and white Start Icon to the right of the schedule you want to start remotely.
  4. The app will ask you to confirm you want to Remote Start this firing schedule. Click Yes to confirm.
  5. To ensure you never accidentally remotely start your kiln, the app will generate a six-digit verification code in the form of a push notification. Enter those six digits. Click Activate, and your firing will start.TAP Kiln Control Mobile uses two step verification for remote start to enhance kiln safety.
  6. Once your kiln firing schedule has been remotely started, you will be able to monitor your kiln, skip steps, abort firings, or view real-time firing graphs from your TAP Kiln Control Mobile app.

A remote start confirmation push notification on TAP Kiln Control Mobile

Easy as that! Remote Start can save artists significant amounts of time by letting them start their kiln firings or preheat their kilns without having to be next to their kiln.

Download TAP Kiln Control Mobile

If you haven’t tried TAP Kiln Control Mobile, we invite you to do so. TAP Kiln Control Mobile, available on iOS and Android, helps you save time and enjoy peace of mind with:

  • Real-time updates and remote temperature monitoring
  • The ability to create schedules and modify settings from the palm of your hand
  • Modify your kiln firing in real-time

And so much more! And it’s totally free to use, with the option to upgrade to a Premium Subscription for advanced features like Remote Start, which lets you start your firing schedule from anywhere!

Explore TAP Kiln Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use 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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Shopping for Kilns That Have TAP Controllers

Guide for shopping for kilns, with advice on how to pick the right kiln based on your needs as an artist.

If you’re in the market for a new kiln, why not purchase a kiln with the most advanced, easy-to-use kiln controller on the market? When shopping for kilns, the type of kiln controller your kiln comes with will have the single biggest impact on the experience of using your kiln.

Why settle for complicated 3-key and 12-key controllers, small screens, and limited space for saved schedules when you could enjoy intuitive touchscreen controls, large easy-to-read full text displays, and the ability to save an unlimited number of firing schedules with an unlimited number of steps? And that’s not even to mention the convenience and peace of mind of being able to monitor and adjust your kiln firings in real-time with the TAP Kiln Control Mobile app!

Shopping for Kilns: Kiln Manufacturers and Retail Sites That Offer TAP Pre-Installed

If you’re shopping for a new kiln, the easiest solution would be to purchase a kiln that has a TAP Controller as a pre-installed option. So, we’ll start by giving you the inside scoop on these kilns. However, some kiln manufacturers don’t offer TAP as a default pre-installed option – so we’ll also be giving you tips on how to get TAP on the kiln of your choice from any kiln manufacturer!

Hot Shot Oven & Kiln

Hot Shot Oven & Kiln, based in Wisconsin, builds high-end kiln and heat treat ovens, including options for:

All of their kilns are made in America! Hot Shot Oven & Kiln offers the TAP Controller as a pre-installed option for all of their kilns and ovens, pairing the world’s most advanced programmable controller with awesome features like standard solid state relays and patented Cool to Touch Technology to enhance kiln safety.

A glass kiln from Hot Shot Oven & Kiln with a TAP Controller
The Creativity Pro Glass Kiln 24 G by Hot Shot Kiln & Oven integrates intuitive TAP Kiln Controls with Cool to Touch Technology and accessible clamshell design for the ultimate glass art experience.

You can shop for Hot Shot kilns and heat treat ovens that fit your artistic needs on Amazon, on their website, or through our partners at Kiln Frog.

Evenheat

Evenheat prides themselves on building kilns and ovens that offer unparalleled precision, exceptional performance, and enduring reliability. With a reputation spanning over seven decades, Evenheat is another amazing option if you’re shopping for kilns and want the most advanced, easy-to-use digital kiln controller!

All of Evenheat’s heat treat ovens and kilns are American-made, backed by exceptional customer service, and include quiet solid state relays for maximum reliability. They provide a variety of sizes (including stackable configurations!) to fit the needs of ceramicists, glass artists, bladesmiths and heat treat artists.

Evenheat manufactures advanced kilns and knife ovens that include TAP Kiln Controllers
The Evenheat LB 27 is a revolutionary long-blade knifemaking kiln that seamlessly integrates the TAP II Kiln Controller with side-only heating for the ultimate in precision and uniformity.

Interested in shopping for kilns from Evenheat? Check out Kiln Frog!

Jen-Ken Kilns

Family owned and operated since 1951, Jen-Ken Kilns is another great option when it comes to shopping for kilns that come with a TAP Controller. With options for pottery kilns, ceramic kilns, glass kilns, and knife kilns, Jen-Kens Kilns will pair you with an advisor who will help you find the kiln that’s just right for you!

You can shop for Jen-Ken Kilns right from their online shop. After buying your kiln, Jen-Ken will build your kiln, ship it directly to you, and then walk you through the setup process right over the phone!

Mobile Glassblowing Studios, LLC

Mobile Glassblowing Studios, LLC manufactures affordable, high quality, rugged, and versatile glassblowing equipment. While their glassblowing furnaces and dragon kilns are gas-powered, all of their front loading stackable annealer kilns and large front loading glass annealers have built-in TAP Controllers.

While glassblowing is a very different process than kilnformed glass art, the precision of TAP and the convenience of mobile kiln control make it the ideal solution for annealers from both disciplines.

Reputable Kiln Retail Sites

While some of the manufacturers we’ve mentioned sell directly through their website or on Amazon, you can also purchase kilns with TAP Kiln Controllers through the following distributors and retail sites:

  • Kiln Frog: Kiln Frog is an awesome one-stop-shop for everything you kiln-related – including kilns and heat treat ovens by Hot Shot, Evenheat, and Jen-Ken that include TAP!
  • Sheffield Pottery: Pottery clay, glazes, and kilns that include TAP! Sheffield Pottery has been one of the best retailers when it comes to ceramics for over 70 years.
  • Delphi Glass: Delphi Glass sells super high quality supplies for kilnformed glass and heat treating jewelry – including the kilns you need to fire them!

Shopping for Kilns: What Should I Do If the Kiln I Want Doesn’t Offer TAP?

Unfortunately, there are some extremely reputable, high quality kiln manufacturers that don’t offer the advanced convenience of TAP as a pre-installed option yet. We’re working on changing that!

However, TAP Kiln Controllers are compatible with just about any relay-controlled kilns, and we’re happy to do everything we can to work with the kiln manufacturer of your choice to make sure you get the kiln you want, while still being able to enjoy easy-to-use touchscreen controls, the ability to create and save an unlimited number of firing schedules, and the convenience and flexibility of remote kiln control!

If you’re shopping for a new kiln from a brand that doesn’t offer TAP Kiln Controllers as a pre-installed option, we encourage you to reach out to them and ask them about TAP! Then, feel free to email us at info@kilncontrol.com and we’re happy to try to facilitate a 1:1 install for the kiln of your choice.

What Should I Do If I Already Own a Kiln That Doesn’t Have a TAP Controller?

If you already own a kiln that doesn’t have a TAP Controller, then it doesn’t mean you have to purchase a whole new kiln. There are multiple options for integrating TAP into your kiln or oven build – whether you’re building from scratch or looking to upgrade your existing controller!

  • Digital Kiln Controllers: You can purchase TAP Kiln Controllers to integrate in DIY kiln or oven builds.
  • TAP Conversion Kits: We also offer conversion kits for easily upgrading existing automatic controllers to the convenience and precision of TAP – with no or minimal modification to your kilns.
  • TAP Standalone Kiln Controllers: TAP Standalone Kiln Controllers, available in wall mount or tabletop configurations, allow you to seamlessly upgrade manual kilns to TAP.

Explore TAP Kiln Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use 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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All About Kiln Relays

Guide for understanding the difference between different types of kiln relays

No matter what type of kiln or heat treat oven you have, choosing the right kiln relay is super important! Kiln relays play a fundamental role in regulating the temperature of the kiln, as well as ensuring kiln safety. Over the course of this article we’ll be explaining what a kiln relay is, how they work, as well as what type of kiln relay is right for your kiln or oven build.

We’ll also be exploring how TAP Controllers and safety limit controllers like TAP Monitor can help protect you from the consequences of kiln relay failure, so let’s get started!

What Is a Kiln Relay?

Kiln relays are a mechanism that receive signals from the kiln controller and then regulate the amount of electricity sent to the elements of the kiln. Kiln relays rapidly cycle on and off – or “close” and “open.”

When kiln relays cycle on, the circuit closes, and the elements receive electrical current. The kiln element’s electric resistance converts that current into heat, and the kiln gets hotter. When the kiln’s relays cycle off, or opens, it interrupts the current to the elements. This causes the kiln to naturally lose heat.

Kiln relays can open and close extremely fast – ranging from 50 milliseconds for mechanical relays to 20 nanoseconds for solid states relays. This speed, when combined when precise inputs from the kiln controller allows the kiln to execute kiln firing schedules with extreme precision.

Types of Kiln Relays

Not all kiln relays are created equal. They differ by the mechanism they use to open and close the circuit. This mechanism affects their performance, precision, and durability. Kiln relays also differ by their environmental friendliness. For instance, mercury relays are banned in several states and aren’t commonly used for modern kilns, since mercury is highly toxic. Below are explanations of the different types of relays.

Mechanical Relays

Mechanical relays use a physical switch to open and close the relay. That’s why you can hear them click! Mechanical relays are affordable. But since the switch is physical, mechanical relays are more prone to failure. If mechanical relays fail in the open position, your kiln will no longer heat up, which can be a major inconvenience. However, it’s when they fail in the closed position that you have major issues. This causes your kiln to heat up indefinitely – threatening your project and your kiln.

Additionally, since mechanical relays rely on a physical mechanism, they are significantly less precise than other options. And since they have a shorter lifespan, they have a higher environmental cost.

Mercury Relays

Mercury relays use gravity and displacement to open and close the relay. Mercury relays consist of a metal weight in a tube of mercury. Gravity causes the metal weight to fall, displacing the mercury until it closes the circuit. A coil at the top of the tube electromagnetically lifts the weight when it receives current, causing the mercury to recess and open the circuit.

Since mercury relays only use a single moving part, they are extremely reliable – significantly more so than mechanical relays. However, there are some issues with this mechanism. Firstly, it takes time for the displace and recede – so mercury relays have the same level of precision as mechanical relays. Secondly, mercury is highly toxic and exposure to mercury has significant health and environmental risks. These two factors have made mercury relays largely obsolete.

Solid State Relays (SSRs

Solid state relays use semiconductors, electronic parts, and LED or infrared sensors to turn the circuit on and off based on signals from the controller. They do not rely on contact switches or any other moving parts to open or close the circuit. This mechanism has several advantages over other types of kiln relays. First, the lack of moving parts means there is no contact erosion – so solid state relays are extremely reliable and will last pretty much forever, when appropriately rated for the application.

Additionally, the fact that solid state relays rely on electric signals, light, and sensors makes them extremely fast, offering a greater level of precision than any other type of kiln relay. Since solid state relays almost never have to be replaced or thrown away, they are far less taxing on the environment.

What Type of Relay Should You Choose for Your Kiln?

If the summaries above don’t make it obvious, we strongly recommend investing in a solid state relay for your kiln. While they are more expensive than mechanical relays, you’ll end up saving money in the long run by never having to worry about replacement costs. That’s not to mention the potential costs of relay failure, which you exponentially reduce the risk of facing by using an SSR.

Most new kilns have the option for solid-state relays – and your TAP Kiln Controller will be compatible with all three types of relays! If you’ve got an older kiln with mechanical or mercury relays, consider swapping them out for solid-state the next time they need replacement.

How the TAP Ecosystem Helps Protect You from Relay Failure

When we designed TAP, we included all of the quality of life features that we ourselves would want as artists. That included allowing the controller to track usage on kiln components and sending out preventative maintenance alerts, so that artists would be able to replace kiln elements, kiln relays, and thermocouples before they reach the end of their estimated lifespan. All you have to do is enter the life expectancy for your relay(s), elements, and thermocouples provided by your kiln manufacturer or the component’s product sheet!

The TAP Kiln Controller tracks kiln relay usage to provide preventative maintenance alerts to help users replace relays before kiln relay failure occurs.
The TAP Kiln Controller tracks kiln relay usage to provide preventative maintenance alerts to help users replace relays before kiln relay failure occurs.

Additionally, later this year, we’ll be releasing TAP Monitor – the most advanced digital pyrometer and limit controller ever created. TAP Monitor adds the convenience and peace of mind of precise, remote temperature monitoring to your smartphone or tablet. When purchased as a set of configurable components, TAP Monitor can also be wired to a redundant safety relay to act as a safety limit controller, making sure your kiln shuts off safely in case of relay failure.

Explore Kiln Control Solutions by SDS Industries

The TAP Ecosystem includes a host of solutions to enhance kiln safety and help you prevent (or safely respond to) kiln relay failure. In addition to being the most advanced, precise, and easy-to-use programmable digital kiln controllers on the market today, the TAP and TAP II Controllers by SDS Industries provide advanced diagnostics, preventative maintenance alerts, and remote real-time kiln monitoring and error alerts via TAP Kiln Control Mobile app. These features help you prevent and proactively address any potential failures in your kiln or oven build.

Additionally, our soon-to-be released TAP Monitor Digital Pyrometer & Limit Controller can be added to any kiln or oven build, regardless of your current kiln control method, to provide safety redundancy and real-time remote kiln monitoring.

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 the most advanced programmable digital kiln controllers for sale.

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Exploring 9 Different Kiln Formed Glass Art Techniques (Plus Examples!)

An overview of different kiln formed glass techniques such as fusing, casting, and slumping.

What is kiln formed glass? When exposed to heat, glass becomes soft and malleable. This allows glass artists to alter its shape or fuse multiple layers of glass together to create new textures or color combinations. At high enough temperatures, glass even liquefies, allowing artists to pour it into (or over) a mold or contour to create new forms.

Once the artist has achieved the desired effect, the glass is allowed to slowly cool and stabilize (or anneal). And the result is kiln formed glass!

9 Types of Kiln Formed Glass Techniques

One of the most exciting parts of being a glass artist is combining various kiln formed glass techniques to create unique, one-of-a-kind glass art. Once you understand these different glass firing techniques, the only limit is your creativity (as well as the capabilities of your glass kiln and glass kiln controller)!

Glass artists like Jill Gary from Jill’s Design combine multiple kilnforming glass techniques to create one-of-a-kind kiln formed glass pieces using her TAP Controller.
Glass artists like Jill Gary from Jill’s Design (who’s a proponent of TAP Controllers!) combine multiple kilnforming glass techniques to create one-of-a-kind kiln formed glass pieces.

Below is an overview of nine different kilnforming techniques – to give you inspiration for your next kiln formed glass art project!

1. Fused Glass

Fusing glass is a kilnforming technique that involves heating two or more layers of glass, and then allowing them to cool, so that they join together to form a single piece of kiln formed glass.

How fully the multiple layers of glass fuse together depends on your firing temperature. The hotter the kiln, the more uniform the fuse! Below are several different types of glass fuses:

  • Full Fuse: The layers of glass are heated up until they liquefy and completely merge together, cooling to form a single, smooth piece of kiln formed glass. Full fusing can be used to create unique and beautiful color combinations.
  • Contour Fuse: Contour fusing uses a lower firing temperature than a full fuse. In contour fusing, the different layers of glass are heated up enough to fully join together while remaining distinct separate layers. In contour fusing, both layers of glass get hot enough to lose some of their initial shape, becoming smooth at the edges.
  • Tack Fuse: Tack fusing involves even lower temperatures than contour fusing. In tack fusing, different pieces of glass are heated up just enough to join together at the point of contact, with both layers retaining their original shape. Tack fusing can be used to create new textures or shapes.
Barbara Elias used a tack fuse technique known as “freeze and fuse” to create a three dimensional effect for the flowers in this glass art piece.
Barbara Elias (another artist who uses TAP!) used a tack fuse technique known as “freeze and fuse” to create a three dimensional effect for the flowers in this glass art piece.

As you can imagine, glass fusing is a versatile kilnforming technique that lets you craft new textures, colors, and even shapes! However, it’s important to make sure that the different layers of glass are compatible. Fusible glass has a higher quality grade than standard glass. Additionally, the different layers of glass need to have compatible viscosities (which isn’t always indicated by matching COEs!).

2. Glass Draping

Glass draping is another popular kiln formed glass technique. Glass draping uses heat and gravity to change the shape of a sheet of glass. For glass draping, you “drape” the glass sheet on top of a convex mold and heat up the glass until it at least partially liquefies. Gravity ensures the molten glass drapes around the convex mold. Higher temperatures lead to more dramatic results. Glass draping can be used for everything from creating conventional plates and bowls to producing abstract, other-worldly shapes!

3. Slumped Glass

Slumping is just like draping, only inversed! For slumping glass, a glass sheet is placed inside a concave mold. The glass is then heated up until it partially liquefies, taking on the shape of the mold. Since slumping glass occurs within the mold, it leads to more predictable results, and is used to create plates, bowls, cups, or decorative molds. The higher the temperature, the more fully the glass takes on the shape of the mold.

4. Glass Casting

Glass casting is similar to slumping. However, with glass casting enough glass is placed within the mold to fill it entirely – so that when the glass melts and then cools, it anneals into a solid object. Glass casting is a kiln formed glass technique that’s used to create ornaments, paper weights, and standalone glass art.

Brittany Gabel, VP & Chief Creative Officer of SDS Industries, used glass casting to create the distinct texture on the outside of this glass cup.
SDS Industries’ very own Brittany Gabel (VP & Chief Creative Officer) used glass casting to create the distinct texture on the outside of this glass cup.

 

5. Glass Crackle

Glass crackle is a decorative kilnforming technique that most typically involves fusing together three layers of glass. The middle layer of glass is then shattered in a controlled method – or you can create the “crackled” middle layer using glass frit and fiber paper to create a crackled effect once it’s heated and allowed to melt. During glass crackling, the three layers of glass are fused together, and the outer layers are left intact so that the final piece retains a smooth (and safe!) outer layer.

There are also several alternative methods to create a crackle effect, some of which use distilled water and glass powder, which you can read about here!

Glass frit powder is used in kiln formed glass art projects for filling spaces or creating textures.
Glass frit is ground fusible glass that is used for filling spaces or creating crackled, mosaic, grainy textures, adding fine details to glass art, or for casting. Picture courtesy of Oceanside Glass & Tile, which can be purchased through our partners at Delphi Glass.

 

6. Pot Melting

Pot melting is another decorative kilnforming technique that involves allowing glass to melt through a hole in the bottom of a pot – onto a primed kiln shelf or into a contained mold – to create swirls and ripples and other textured effects!

Watch our partners at Delphi Glass walk you through how to incorporate pot melting into your kiln formed glass projects.

7. Fire Polishing

Fire polishing is a “finishing” technique. Typically used after cold working glass, the glass is then heated up until it returns to its original shiny and smooth state.

8. Bubble Squeezing

A bubble squeeze is a “preparatory” technique before kilnforming glass. Bubble squeezing is used to create more even fuses by slowly heating up glass to allow trapped air to escape. Bubble squeezing reduces the number of bubbles, as well as their size, resulting in more uniform (and structurally sound!) kiln formed glass.

9. Annealing

Finally, we get to annealing, which is the final step in kilnforming glass. Annealing glass is less of a technique, and more of a necessity! Annealing is a controlled cooling process. If you allow kiln formed glass to cool too quickly, it leads to all kinds of issues – like thermal shock, breakage, shattering, stress fractures, and structural weakness. An advanced glass kiln controller like TAP or TAP II by SDS Industries automatically (and precisely) cools glass at a controlled, highly specified ramp rate – keeping both glass and artists from being exposed to unnecessary stress!

Glass Supplies for Kilnforming Glass

Excited to get started? Before getting started on your next kiln formed glass project, you’ll need the right supplies! Below are brief explanations of the different glass supplies you’ll need for kilnforming!

Glass Kilns and Glass Kiln Controllers

Of course, to kiln form glass, you’ll need a kiln – and a kiln controller – that’s capable of glass firing. Glass kilns are specifically designed to heat glass to very precise temperatures so it can be fused, slumped, or cast.

(Some glassblowing artists also use a dedicated annealing kiln to slowly cool down blown glass that’s been heated outside of kiln to improve its durability and prevent the glass from experiencing thermal shock).

However, in addition to your kiln, it’s important to choose the type of kiln controller. TAP Kiln Controllers by SDS Industries provide glass artists with an advanced programmable digital controller that’s precise, simple, and easy-to-use. TAP Controllers are capable of executing complex schedules with multiple ramp rates to ensure your kiln formed glass comes out just the way you wanted! With TAP Controllers, you can store an unlimited number of firing schedules – so you always have all your glass firing schedules on-hand for when you need them. And with TAP Kiln Control Mobile, you have the convenient option to control and monitor your kiln formed glass firing right from your phone or tablet!

Types of Accessory Glass

Once you have the right kiln and the right kiln controller, you’ll also need glass. Glass used for kilnforming – also known as accessory glass – comes in several forms:

  • Glass Frit: Glass frit is ground fusible glass that is used for filling spaces or creating crackled, mosaic, grainy textures, or for adding fine details to glass art.
  • Sheet Glass: Available in a variety of sizes, sheet glass is used for kilnforming, fusing, and mosaics.
  • Glass Rods, Noodles, Stringers, and Ribbons: Glass rods, noodles, and stringers are long, narrow strips of glass that are fused to other pieces of glass to create patterns, textures, or other artistic effect. Glass ribbons are a flatter, wider alternative that are perfect for fusing.
  • Glass Confetti: Glass confetti consists of small, irregular, ultra-thin flakes of glass and are used for adding touches of color to your kiln formed glass.
  • Glass Billets: Billets are precisely cut sheets of fusible glass that are the perfect size for casting.
Glass rods, noodles, and stringers are used for kiln formed glass projects.
Photograph of glass rods, noodles, and stringers courtesy of Oceanside Glass & Tile.

Accessory glass comes in all sorts of colors and levels of translucence – so that you can create the perfect effects for your kiln formed glass projects. Just make sure that when you’re shopping for accessory glass, that the glasses you choose are compatible. A good place to start is by making sure that the glasses have matching COEs – or coefficients of expansion – which means they’ll expand or contract at the same rates when heated up or cooled down. However, there are other factors that affect compatibility, so it’s always recommended that you do plenty of research before purchasing glass and start by doing a test fuse for glasses you’re not familiar with!

Explore Glass Kiln Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries provide artists with the most advanced, precise, and easy-to-use glass kilns 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:

Upgrade Your Glass Kiln with TAP Digital Kiln Controllers

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Standalone Kiln Controllers: Wall Mount Kiln Controllers and Tabletop Kiln Controllers

TAP Standalone Wall Mount Kiln Controller allow you to upgrade from manual to automatic kiln controls.

For newer artists, figuring out what type of kiln controller you need for your kiln or oven build can be an intimidating prospect. Do you need a conversion kit? A standalone kiln controller? A tabletop kiln controller? Don’t worry, below is a simple cheat sheet for understanding kiln controller categories:

  • Digital Controllers: For new kilns or oven build or competent DIYers. Digital controllers include the controller, the faceplate, and a wiring harness pigtail.
  • Conversion Kits: For upgrading automatic kiln controllers that are already installed on your kiln or oven. Conversion kits include the controller, the conversion box, a wiring harness adapter, and mounting hardware to facilitate seamless installation.
  • Standalone Kiln Controllers: For easily upgrading manual kilns to automatic controllers. Standalone kiln controllers include the controller, standalone controller housing, a power cord, and a thermocouple for plug-and-play installation.

Configurations of Standalone Kiln Controllers

For easily upgrading a manual kiln, a standalone kiln controller is the go-to choice. With standalone kiln controllers you can completely transform your kiln firing experience – from having to constantly monitor and manually adjust the temperature of your kiln to automatically executing your firing schedules with a precise, easy-to-use touchscreen controller that offer features like remote kiln control and temperature monitoring.

SDS Industries offers TAP Standalone Controllers in two different configurations: wall mount kiln controllers and tabletop kiln controllers.

The Difference Between Wall Mount Kiln Controllers and Tabletop Kiln Controllers

From a feature and functionality standpoint, TAP Wall Mount Kiln Controllers and TAP Tabletop Kiln Controllers are exactly the same. In either configuration, you have the option to choose between a TAP or a TAP II, both of which give artists the most precise, easy-to-use kiln control experience available.

Tabletop kiln controllers make upgrading your manual kiln extremely easy.

TAP Standalone Controllers give artists the ability to:

  • Seamlessly upgrade their manual kiln to the most advanced digital kiln controller on the market.
  • Easily manage and execute your firing schedules with an intuitive touchscreen and logical menus that allow you to immediately begin programming and operating your kiln.
  • Enjoy the ability to create, save, edit, and name an unlimited number of firing schedules – each with an infinite number of custom steps – so that you never have to recreate a schedule again!
  • Find the schedule you need when you need it with full alpha-numeric text displays.
  • Save time and maximize peace of mind with remote kiln control and real-time monitoring through the TAP Kiln Control Mobile app.
  • Ensure maximum consistency and stay fully informed with PID-driven precision, advanced diagnostics, error reports, graphical firing logs, push notification alerts, and more!

The only real difference is which setup fits your workspace or studio better.

Pros and Cons Wall Mount Kiln Controllers

For smaller workspaces, or ones where flat surface space is at a premium, a wall mount kiln controller allows for a compact, semi-permanent installation. With wall mount kiln controllers, there is minimal risk that the controller gets damaged by gravity or other environmental exposure. Additionally, it’s easy to mount the controller close to the kiln for clean installs in terms of having the wiring to the power outlet and to the thermocouple out of the way.

However, a wall mount kiln controller does require more work in terms of installation – and will require a surface that you can mount the controller to.

Wall mount kiln controllers allow for a clean, semi-permanent installation for your kiln controller upgrade.

Pros and Cons of Tabletop Kiln Controllers

While standalone kiln controllers are designed for easy installation, installing tabletop kiln controllers is as simple as it gets. All you need is a flat surface in proximity to the kiln to set down the controller! However, there is the risk that you accidentally knock over your controller, or the controller gets damaged by setting down another item on its tabletop.

Additionally, tabletop kiln controllers may require modifications to your workspace for a clean installation depending on where the tabletop is in relation to your kiln.

Explore TAP Standalone Kiln Controllers

Whether you’re looking for a wall mount kiln controller or a tabletop kiln controller, SDS Industries has got you covered! The TAP and TAP II Controllers are available as standalone kiln controllers in both configurations! With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Control Mobile app, TAP Standalone controllers make the perfect upgrade to your manual kiln or heat treat 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:

CTA for TAP Kiln Controller Shop Pages

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Setpoint Controllers: Single Setpoint vs Multi-Setpoint Controllers

Multi-setpoint controllers are capable of executing schedules with multiple steps, while single setpoint controllers can only automatically execute schedules with a single setpoint.

During a firing schedule, a setpoint is the pre-set firing temperature the kiln must reach in order to successfully complete each step. A setpoint controller measures the kiln’s temperature and cycles the relays to ensure the kiln reaches the desired temperature.

Setpoint controllers, also known as process controllers, are programmable digital devices that automatically execute firing schedules. All the user has to do is enter the desired setpoint(s), and the controller takes care of the rest!

What Is the Difference Between a Single Setpoint and a Multi-Setpoint Controller

When it comes to kiln firing schedules, there are varying degrees of complexity. For firing glass or ceramics, the kiln often has to reach multiple setpoints over multiple steps. However, most heat treat processes – such as those used for making knives, jewelry, or firing metal clay – only involve a single setpoint.

A multi-setpoint controller is capable of executing complex schedules with multiple setpoints. For instance, the TAP and TAP II Controllers by SDS Industries can accommodate schedules with an infinite number of steps! However, that level of robustness might be a little excessive for users who only work in heat treat, which is where single setpoint controllers come into play.

The TAP II is capable of executing schedules with an unlimited number of setpoints.
The TAP II Kiln Controller is capable of automatically executing schedules with an unlimited number of setpoints.

Single setpoint controllers are greatly simplified and only require the user to enter the single setpoint they need for each individual heat treat process.

Single Setpoint Heat Treat Processes

While a multi-setpoint controller is capable of executing schedules with a single setpoint, below are metal heat treat processes that only require a single setpoint:

  • 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.
  • 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.
  • 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. While annealing can be completed with a single setpoint controller, it will be necessary to use sand or insulated blankets to make sure the metal doesn’t cool down too quickly outside of the oven. However, a multi-setpoint controller can be used to slowly anneal metal within the oven.

Introducing TAP&Go: The Most Easy-to-Use, Streamlined Single Setpoint Controller

In the past, single setpoint controllers were far less featured than their multi-setpoint counterparts. This forced heat treat artists to choose between advanced multi-setpoint controllers that required paying for functionality they didn’t need, or simplistic single setpoint controllers that lacked precision, ease-of-use, or required constant monitoring to know when the oven had reached the right setpoint.

SDS Industries has set out to change that with our 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.

The TAP&Go is a simplified single setpoint controller designed specifically for heat treat.
The TAP&Go is a simplified single setpoint controller designed specifically for heat treat.

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 takes the design principles 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:

Explore our line of TAP Electric Kiln Temperature Controllers.

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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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Understanding and Preventing Kiln Relay Failure

Learn all about kiln relays and how to prevent kiln relay failure.

Three words no artist wants to hear: kiln relay failure. At best, kiln relay failure can be an annoyance that disrupts your project mid-schedule. At worst, kiln relay failure can pose a threat to the safety of your household and your property. However, the good news is that with foresight, proper maintenance, and the right equipment, kiln relay failure can mostly be avoided.

Over the course of this article, we’ll be discussing:

  • How kiln relays work.
  • Why (and how) relays fail.
  • How to choose a kiln relay that minimizes the chance of failure.
  • How to easily track preventative maintenance to know when to replace relays.
  • Kiln safety equipment to invest in to mitigate damage in case of relay failure.

How Kiln Relays Work

To understand why kiln relays fail, first, it’s important to understand how they work. In simple terms, kiln relays are a switch. Based on input from the kiln controller, relays cycle on and off – closing and opening the circuit to the kiln’s element.

When a relay closes, electric current flows to the kiln’s elements, increasing kiln temperature. When a relay opens, no current flows to the element, and the kiln cools down. Relays open and close at variable rates, allowing the kiln to reach precise firing temperatures.

Types of Kiln Relays

Different types of kilns relays have different types of mechanisms that allow them to cycle on and off. In modern kilns the most common types of relays are mechanical relays and solid-state relays. However, some older kilns still use mercury relays – so we’ll be explaining all three mechanisms:

  • Mechanical Relays: Mechanical relays have the most moving parts. Mechanical relays use an electromagnetic switch that physically moves each time the relay cycles on and off. That’s why you can hear them click each time they cycle when the kiln is operational!
  • Mercury Relays: Mercury relays work through gravity and displacement. Mercury relays use a metal weight in a tube of mercury. Gravity causes the metal weight to fall, displacing the mercury until it closes the circuit. A coil at the top of the tube electromagnetically lifts the weight when it receives current, causing the mercury to recess and open the circuit.
  • Solid-State Relays (SSRs): Solid-state relays use semiconductors and electronic parts to turn the circuit on and off based on signals from the controller. They do not rely on any moving parts to open or close the circuit.

Why Relays Fails

Kiln relay failure largely comes down to failure of their switch mechanism. As you might expect, mechanical relays have the most moving parts and are subject to normal wear and tear. They will fail eventually, it’s just a matter of when.

Mercury relays only have a single moving part and aren’t subject to the same contact erosion in high current applications. They’re extremely reliable, lasting for millions of cycles.

Solid-state relays have no moving parts. As such, they are supremely reliable and aren’t subject to any wear and tear. Their only Achilles heel is heat. Solid-state relays must be appropriately cooled via heat sink to maintain proper performance and prevent melting.

Kiln relay failure can occur in one of two positions. A relay can get stuck open, in which case your kiln will fail to heat up. While this is inconvenient and can put your project on hold, it’s far preferable to when a relay gets stuck closed! When kiln relays get stuck in the closed position, the kiln heats up indefinitely, posing significant risk to your household and property.

However, there are safety precautions you can take to circumvent any potential damage, which we’ll be discussing later in the article.

Choosing the Right Type of Kiln Relay

As you can see from the descriptions above, mechanical relays are far more likely to result in kiln relay failure. Mercury relays, while reliable, use the highly toxic liquid metal, mercury, to perform switching. As such, they’re largely obsolete and are even outlawed in states such as California.

That means that, realistically, your best option to prevent kiln relay failure is to purchase a solid-state relay. Not only are SSRs superior in lifespan and environmental concerns, but they cycle on and off significantly faster than other types of relays, resulting in superior performance and precision.

Most new kilns have the option for solid-state relays. While TAP Kiln Controllers are compatible with all three types of relays, we strongly encourage our customers to invest in a solid-state relay. The upside far outweighs the cost. If you’ve got an older kiln with mechanical or mercury relays, consider swapping them out for solid-state the next time they need replacement!

Additionally, whether you’re shopping for mechanical relays or solid-state relays we suggest purchasing from reliable, reputable manufacturers.

Preventative Maintenance

In addition to selecting the right type of relay, preventative maintenance is key to preventing kiln relay failure – especially if you’re using a mechanical relay.

As far as preventative maintenance for solid-state relays, really the biggest consideration is making sure that they are rated properly for the application and that you install the relay correctly with a heat sink to prevent the relay from overheating. Beyond that, we encourage you to store your kiln inside to avoid exposing electrical components to the elements and pay attention to your controller’s error notifications (assuming you’re using an advanced controller such as TAP that provides real-time diagnostics, as well as detailed error and firing logs).

Mechanical relays require much more proactive preventative maintenance. Mechanical relays have a finite lifespan that’s impacted by how often you use your kiln and the types of kiln firing schedules you use. However, you can find an estimated life expectancy for the number of cycles your mechanical relay is rated for from your kiln manufacturer or the relay manufacturer’s product sheet.

With advanced controllers from temperature controller manufacturers like SDS Industries, you can input life expectancy for your relay(s), elements, and thermocouples. The controller will then track the usage of these components and send you preventative maintenance alerts. This helps you replace your kiln relay before it fails.

The TAP Kiln Controller tracks kiln relay usage to provide preventative maintenance alerts to help users replace relays before kiln relay failure occurs.
The TAP Kiln Controller tracks kiln relay usage to provide preventative maintenance alerts to help users replace relays before kiln relay failure occurs.

 

Kiln Safety Equipment

Investing in the right type of kiln relay and being diligent about preventative maintenance significantly reduces your chances of facing kiln relay failure. But there will always be a non-zero chance that your relay fails, and an ounce of prevention is worth a pound of cure!

We strongly encourage our customers to invest in kiln safety equipment that keeps you safe in case of kiln relay failure. This equipment includes:

  • A reliable fire extinguisher to keep nearby your kiln to mitigate any damage in the case that your relay gets stuck closed.
  • An advanced kiln controller that provides precise inputs to your kiln relay and monitors your kiln for discrepancies to provide you with real-time error alerts.
  • A kiln control mobile app that provides real-time temperature monitoring and push notification alerts and alarms to your smartphone, so that you can spot any warning signs in real-time and respond appropriately.
  • A safety limit controller (such as the soon-to-be released TAP Monitor!) that can be wired to a safety relay to provide max temp safety shutoff even if your primary kiln relay fails.

 

Explore Kiln Control Solutions by SDS Industries

The TAP Ecosystem includes a host of solutions to enhance kiln safety and help you prevent (or safely respond to) kiln relay failure. In addition to being the most advanced, precise, and easy-to-use programmable digital kiln controllers on the market today, the TAP and TAP II Controllers by SDS Industries provide advanced diagnostics, preventative maintenance alerts, and remote real-time kiln monitoring and error alerts via TAP Kiln Control Mobile app. These features help you prevent and proactively address any potential failures in your kiln or oven build.

Additionally, our soon-to-be released TAP Monitor Digital Pyrometer & Limit Controller can be added to any kiln or oven build, regardless of your current kiln control method, to provide safety redundancy and real-time remote kiln monitoring.

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 programmable temperature controllers.

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The Difference Between a Limit Controller and a Process Controller

Learn more about the difference between limit controllers and process controllers.

When it comes to kiln temperature controllers, there are two broad categories: process controllers and limit controllers. So, what’s the difference?

Process Controllers vs Limit Controllers: Function & Use Cases

If you use an at home kiln or a studio kiln, chances are you’re more familiar with a process controller. Process controllers, also known as programmable digital controllers, automatically adjust kiln temperature to execute kiln firing schedules with very little user involvement.

Limit controllers, on the other hand, are currently more commonly used with ICS control systems, industrial kilns, and manual kilns. Also known as high limit or safety limit controllers, limit controllers monitor kiln temperature and ensure that the kiln automatically shuts off if the kiln exceeds a specified temperature.

Process controllers execute process; limit controllers enforce limits. Process controllers are a primary kiln control method. Limit controllers, while not usually suitable to be the primary control method, are an important part of kiln safety and can protect you, your equipment, and your property in the case of relay or system failure.

The TAP II Kiln Controller is an example of a process controller that allows users to automatically execute full firing schedules.
The TAP II Kiln Controller is an example of a process controller that allows kiln operators to automatically execute full firing schedules.

 

If I Already Have a Process Controller Why Would I Need a Limit Controller?

If you’re reading this article and you already have a process controller, you might be asking: Why would I need a limit controller?

The answer? Safety.

Even though advanced kiln controllers, such as TAP and TAP II, provide max temperature safety shutoff in case of relay failure, redundancy is the key to safety. Safety limit controllers such as TAP Monitor add an additional layer of safety. When installed and wired to a redundant safety relay, TAP Monitor will automatically shut off your kiln if it exceeds a specified temperature – even if your primary relay fails.

Benefits of TAP Monitor Limit Controller

TAP Monitor is an advanced, user-friendly kiln limit controller and pyrometric device that can be paired with any manual or automatic kiln controller to provide safety shutoff and remote temperature monitoring.

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:

  • Wire TAP Monitor to a safety relay to provide redundant safety shutoff.
  • 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.
  • Easily add precise, real-time digital temperature readings to their manual kiln or oven.
  • Pair TAP Monitor with their existing automatically or manually controlled kiln for remote monitoring.

The TAP Monitor is a limit controller that adds remote temperature monitoring and safety shutoff for kilns.

Explore Kiln Control Solutions by SDS Industries 

In addition to the TAP Monitor Limit Controller, the TAP Ecosystem includes a variety of programmable kiln controllers that give artists complete control of their kilns. 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 programmable temperature controllers.