Quick Answer – Can Pottery or Ceramic Kilns Be Used for Glass?
Yes, you can use ceramic and pottery kilns for glass, but they are not considered ideal. Glass is worked at much lower temperatures than is required for the majority of pottery and ceramics. If you want to work glass in a ceramic kiln, you will need controllers that allow you to adjust the firing process’s time and temperature accordingly.
Difference Between a Glass Kiln vs. Ceramic Kiln
Glass, pottery, and ceramics are very different media. While ceramics and pottery have very similar firing requirements, glass is an entire world of its own.
Because of this, the kilns designed for glass are very different from those intended for firing pottery and ceramics. Here are the major differences you will notice between pottery kilns and glass kilns.
Size and Shape
Ceramic kilns can range in size from small hobby models that can only hold one piece of pottery at a time to large industrial units than accommodate vast amounts of work. Even most pottery and ceramic shops have a kiln to hold a half dozen pieces with the right furniture. These kilns can be round, square, or any other shape.
Working with glass requires a more direct form of heat. Because of this, they are generally much shallower than pottery kilns and only allow for only one layer of wares to be fired at a time.
Glass is typically worked at temperatures of 1,100 1,500 degrees Fahrenheit (600 to 820 degrees Celsius). On the other hand, The firing range of most ceramics and pottery typically ranges from 2124 degrees F to 2264 F (1162-1240 degrees C) but can be as high as 2,400 degrees F (1,300 degrees C). Ceramic Bisque, which is fired at around 1,850 degrees F (1,000 degrees C), is one exception.
As you can surmise, these temperature differences require kilns built to different temperature tolerances.
Most ceramic and pottery kilns can easily reach the working range of glass, but few glass kilns can operate at a high enough temperature to fire pottery. Even those that can will quickly be damaged.
When working with glass or ceramics, it is important that they be heated evenly. But, because glass is normally flat and pottery and ceramics come in all shapes and sizes, this means supplying heat in a very different manner.
There are exceptions, but as a general rule, Kilns intended for glassworks have their heating elements placed in the top where they can radiate evenly across the largest horizontal area.
In contrast, kilns designed for ceramics and pottery are most often heated from the sides. This is to heat the firing chamber uniformly from top to bottom.
You should note that duel medium kilns have heating elements both in the top and on the sides. On most models of this type, you swap from one to the other with a switch.
What is the best kiln for glass and ceramic work?
If you want to work with both glass and ceramics, your best bet is to purchase a dual media kiln. These are designed to allow you to work with pottery ceramics and glass by adjusting the kiln’s settings. Like most compromises, though, they are not optimum for any specific purpose. If you are a serious artesian, it is best to have separate specialized kilns.
Why are glass kilns heated from the top?
Glass projects are most often reasonably flat. This requires them to be heated uniformly across their entire surface to avoid stress and cracking. The best way to accomplish this is to put them relatively close to the heat source. That way, the entire piece “sees” the heat, and stressors are avoided.
Because glass is actually a liquid and becomes softer and droops when heated, this makes being heated from above most advantageous.