Most reach about 2000 degrees F or 1093 degrees C. I knew that for glass I need around 1500 degrees F, and speed was not that important since fused glass is heated slowly.
How big do you need your kiln to be? Is there any way to add extensions to the kiln later?
When looking at specifications, remember that the inside of your kiln will be smaller than the outside. The smaller the kiln, the smaller the price. However, I knew the small kilns, which have about a 6 inch shelf diameter, would be too small to slump glass bowls. My pocket book would not allow me to get a super big kiln. Therefore, I decided to find a kiln that was in the medium/small size. I also wanted a kiln that I would allow me to make it larger, especially the height since I might want to put casting flasks in it one day.