A ceramic kiln controller is as essential as a rudder for a ship. Without this crucial component, you may be able to move forward, but whether you will reach the desired destination remains in question. It is the same with a regulator or kiln controller: a ceramic kiln simply cannot do without a control, certainly not the current generation of kilns.
Modern ceramic kilns do not have an on or off switch, only a plug input (connector). Selecting a new ceramic kiln is a challenge in itself, let alone finding the right controller. This is especially true if you deviate from the standard controllers that come with the kiln.
Personally, I’ve always chosen a kiln controller that suited better my specific needs than the standard option. More than twenty years ago I chose the Bentrup TC 507, which I am still very satisfied with. However, the new generation of controllers offers significant advantages, such as SmoothPOWER for solar energy and Superwise for logging and an online firing livestream.
Is it time for an upgrade?
Manufacturers of ceramic kiln controllers
Potters in the EU have an extensive choice of ceramic kilns. Kiln builders such as Keramikos, Ve-Ka, Kittec, Westeneng, Mojo, Blaauw, Rohde, Nabertherm, Lac, Skutt and others offer a wide range.
Fewer manufacturers develop operating systems. All kiln builders supply almost all their kilns with a standard control system from one of the following manufacturers:
Some ceramic kilns have the name of the kiln manufacturer on the controller, such as Pyrothek (Bentrup), Nabertherm (Hermes), Skutt (Bartlett) and Rohde (Stafford). However, these operating systems are produced by the mentioned specialized developers. Other kiln builders, such as Keramikos, Ve-Ka, Westeneng, Toma, Colpaert and Mojo, supply their kilns with a Bentrup or Hermes control, without changing the name.
It is crucial to be well informed when investing in a ceramic kiln. It is equally important to make the right choice for the controller that will regulate the kiln. The standard controller will function well, but it may not fully meet your current or future needs.
Ceramic kiln controller: the essential functions
Let’s take a step back and take a look at the essential functions of a ceramic kiln controller. A high-quality controller provides precise temperature inside the kiln, crucial for the successful firing of ceramics. Important points for ceramists to pay attention to are:
- Temperature accuracy: The controller should keep the temperature within the kiln consistent with minimal fluctuations.
- Programmability: The ability to set various firing programs, the number of steps per program and the number of programs that can be saved.
- Convenience: An intuitive interface simplifies kiln setup, saving time and reducing the chance of errors during the process.
- Durability: Due to the high temperatures and frequent use, a regulator must be able to withstand the harsh conditions in the firing room.
- Safety: Features such as automatic shut-off and overheat alarms are essential for user safety and kiln life.
Essentially, the regulator controls the kiln elements (coils). By periodically switching them on and off, the heat supply in the kiln is regulated. This is done via one or more relais (on and off switches). When there is current on the coils, they give off heat; When the power is turned off, they cool down again.
Because the controller is connected to one or more thermocouples, it can calculate whether more or less heat (power supply) is required to follow the pre-programmed firing curve.
Choices of kiln controllers at a glance:
All controllers available within the EU must meet minimum requirements of safety and durability. This in accordance with the EU directives. Controllers perform all essential functions, including the crucial task of regulating the temperature inside the kiln.
The experience of ease of use varies from person to person. I find the programming method of Bentrup controls logical after studying the manual. Others may prefer the Hermes or Bartlett controls.
Besides ease of use, there are other important considerations. Below is an overview of all the questions I find necessary to know about the ceramic kiln controller.
Does the ceramic kiln controller have:
The possibility of a delayed start
Although I never use this myself, it is a useful feature if you want the kiln to start at a time when no people are present. For example, for a teacher who wants to start the kiln at school in the evening before he or she goes home.
Three or more firing steps/segments per program
A minimum of three steps are necessary for most firing types. This includes the start up to about 150 °C (slowly), the mid-range to about 1000 °C (as fast as possible), and the final step to the top temperature (depending on the desired glaze results). But more steps, of course, offer more freedom to program other firing curves.
The possibility of setting a soak time
A “soak” is a period of time during which the kiln remains at a constant temperature. This is usually possible after each step, but is mainly used at the top temperature. It is not necessary, but can help even out the temperature in the kiln.
A delayed or slow cooling
For some glazes, especially crystal glazes, a programmable cooling rate is essential because they benefit from slow cooling.
How many programs can be saved
I experiment a lot with glazes at different temperatures and have therefore programmed and saved a lot of firing cycles. This is only possible to a limited extent with other controllers. This is not a problem if you always fire at the same temperatures.
Fixed firing curves (pre-programmed)
Some controllers offer fixed programs for biscuit and glaze firing. These are usually fine, but I find them unnecessary. If you have no idea which firing program to set, you can take the advice from the manual or from the internet, such as glazy.org. Without fixed programs, there is more room for storing your own programs.
Error messages
All controls have this feature, but some are more comprehensive than others. For example, the error messages are saved, even if the controller is switched off after firing. As soon as things go wrong, you will find this feature very important 🙂
Multiple controllable zones
Most kilns have only one thermocouple to measure temperature, but some have two or three. Advanced controllers can control the heating elements independently of each other, equalizing the temperature throughout the kiln.
Adjustable type of thermocouple
Three types of thermocouples are common in kilns: K, S, and R. When replacing a regulator, make sure that the correct one is selected, otherwise the measured temperature will not be correct. If this is not adjustable, the thermocouple in the kiln may need to be replaced.
Adjustable type of relais
Most kilns work with magnetic relais (switches). These cannot shift quickly (no faster than approx. 1 x every 30 seconds) and also wear out if they are shifted too quickly. A Solid State Relay (SSR) does not switch mechanically. As a result, this type shifts faster, allowing the regulator to control the temperature more accurately. But only if this can be set in the controller.
Connectors: where is the (emergency) exit
Finally, it is important to discuss the output plug or connector of the various controllers. When you purchase a new kiln, the supplier will make sure that the controller has the correct type of connector plug to fit the kiln’s connecter. However, when replacing a controller, you should also pay attention to the type of connector plug.
In the EU, the following three connectors are mostly used:
- HAN 7 D (square)
- HAN 15 D (flat)
- CPC14 (round)
In addition, the pin configuration must match the kiln manufacturer’s specifications. This configuration can usually be found in the controllers manual. In general, the different controllers can be connected to the different brands of kilns without any problems, provided that the connector matches (especially if the old controller is from the same brand). However, always check with the manufacturer of the kiln! If the pin configuration does not match, the controller will not work.
Controllers with extra features
So, there is a wide range of options to consider and compare. Think about which components are essential for your firing process and budget.
Example:
The Bentrup TC44 is an economical choice, but it has limited features for setting firing curves, such as the lack of an adjustable cooling rate. If you need more programming steps, including a specific cooldown rate, then the TC88 could be a better investment.
So now we have all the information… or have we? There are additional features such as a firing log, a livestream of the firing (via Wi-Fi or Bluetooth) and Solar Ready options.
Fortunately (or unfortunately) the work of a ceramist is never finished.
We’ll save this topic for the next blog. 🙂
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