Once you’ve determined the type of kiln you want, the next question is what shape, size and depth will provide the most flexibility for you. No one usually wants to do the same stuff over and over, so flexibility is key! Here are some considerations when it comes to shape, size and depth:
What shape do you want?
Most folks are more concerned about kiln size than shape, but it is shape that provides the most flexibility. Kilns come in a few shapes; round/octagon, square, or rectangle/oval. A square or rectangular shelf will ultimately deliver the most flexibility because it will always produce the largest square or rectangle, in addition to the largest circle. A round shelf can only produce a square large enough to contain the corners. Simply stated, a 13” round shelf will produce a 12.5” circle, but only allow a 9” square. But, a 13” square will produce a 12.5” circle, and a 12.5” square.
What size do you want?
The truth is that kiln size does matter. The rule of thumb we’ve always heard is that an artist should purchase the largest kiln they can afford, as they will surely grow to produce larger work as time goes by. Our hunger to do more, learn more, and do it bigger and better than before is amazing! With that said here’s the skinny on size… You are limited by the size of your shelf! There…..we said it. Forget the outer dimensions that are listed in the specifications. The shelf size that fits in the kiln is the rate limiting factor on the size of piece you can produce. We recommend that you choose the shelf size first and the kiln second. Select a shelf that will provide the needed surface area for your largest projects.
How deep should it be?
This is the most overlooked question we’ve found, and the one that usually turns out to provide the most regret if ignored. This is also a question that you must ask with perspective of looking at your future. Today you might only be working flat and shallow, but tomorrow you may want to work deeper and make vessel sinks, or use drop rings, or even pendant lighting draping over tall floral former molds. Once you commit to a depth, you are stuck with it, so go as deep as you think you might ever need to go. Kilns come in various depths from 4.5” – 24”. Keep in mind that a very deep kiln requires more energy to run, and thus will have higher operating costs to heat the chamber. In practical terms, the operating cost between a 9” depth and a 15” is not as significant as the difference between a 9” and a 24” depth.
A few practical considerations...
The rules of physics dictate that a certain amount of energy is required to heat a particular amount of space. What this means is that at a certain kiln size, usually about 15”, a kiln will require more power to function. So…as a general rule, kilns over 15” in size are almost always powered by higher voltage, as they need more amperage to operate.
With all of that said, here is the common sense decision making equation:
If I want bigger than 15” in size (13" shelf) - then I must commit to 240v power.
If I only have 120v power available - then I must stay under 15” in size.
This has no bearing on the shape of the kiln you choose, although the depth will play a part in determining the volume of chamber space that needs to be heated.