How low of the top should the shelf be?

[Havi]

HeLLO EVERYBODY,
I know its the most stupid question on earth, but I do not know the answer to it...
Can anybody tell me what is the recomended / ideal depth of a kiln, for FUSING ONLY???

I have a deep kiln which I bought in order to be able to do both fusing and casting. Right now I am doing only fusing and break my back when I lean down to install staff for fusing.

I decided to put some bricks under the Dysson shelf I have. Then I began to ask myself whether I am not hightening my shelf too much.
I have elements on the top of the kiln and around it.

How low off the rim should the shelf be laid??

Many thanks in advance,

Havi

[Bert Weiss]

Havi, there are no rules. There is more even heat and less even heat. The more even your heat is, the faster you can heat the glass without breaking it.

I've heard a theory that heat evens out beneath the elements at about the distance between coils. (or maybe the height of an equilateral triangle). So, if your elements are 4" apart, place the glass at least 4" beneath the elements. If you need to get closer, then slow down the heatup.

Another theory is that heat radiates evenly for about 12" and then it falls off. I don't think this is an exact paradigm, but it will be much closer at 14" than it is at 18".

Given these 2 theories, side elements, on a fusing kiln, are never a perfect solution, relative to evenivity.

My next generation of fusing kiln design will have equal elements on both roof and floor, none on the side. This will be capable of firing very thick glass, and get a faster heatup and anneal. If you are heating the glass from it's 2 largest surfaces, it will even out faster.