Since I seem to be using up all my tempered glass for flask windows I thought I'd try to temper some. How hard can that be? First try was today, I put a piece of 1/4" plate glass on some kiln furniture. Ans started a program to heat it to 1148F in 180 minutes. Jason had suggested 175F per hour but this is thin, and only 2" by 4". Top number is actual, bottom is setpoint. It overshot about 8F until the fuzzy logic learned the system, then it was about 2F. I was at the neighbor's doing some electrical troubleshooting when it reached 1148F. No worry, I had it on hold after then for 60 minutes. When I got back to it, it had cooled to 950F. I realized I had not programmed it right to simmer at 1148F. Since it had already been there, I ran it back to 1148F and executed hold. Then it took more than a half hour to get ready to pull the glass out. I had my son in law and his grandson in law lined up to shoot the hot glass with an air jet from each side. What went right: Nobody got hurt. What went wrong: Glass had draped over the furniture. Glass was stuck to the furniture. Glass was not tempered. Glass began cracking soon after we chilled it with air jets. Questions I have: Should I have pulled it out as soon as it hit 1,148F to avoid sag. Maybe that would not help. I know commercial furnaces move it continually through on rollers. I thought for automation but it may be to keep the glass flat by continually supporting it at different places. It has to soak long enough to get it all to equilibrium. What could I support it with that would not stick? Stainless steel? Jack said glass used to be hung in tempering furnaces. I may have to come up with a clamp arrangement I think will stand 1,148F. None of the glass was tempered. I broke a lot of it with a hammer.