Thanks for your reply. The glass I used is Spektrum, COE96. I’ll give the firing schedule in F:
1. Ramp in 400F/h to 450F, hold 15 min
2. Ramp in 400F/h to 1000F, hold 15min
3. Ramp in 500F/h to 1150F, hold 20 min
4. Ramp in 500F/h to 1450F, hold 15 min
5. Ramp AFAP to 980F, hold 60 min
6. Ramp 300F/h to 950F, hold 60 min
7. Ramp in 150F/h to 750F, then it’s done.
The dish is a 30 cm square dish, two layers of glass. Sorry for the cm;).
I bought the glass in a package of 13 sheets. All are labeled Fuse compatible. They come from a store specializing in glass where I buy all my glass. I used more sheets of the same glass and there where no problems.
You can just see a scratch on one side of the dish. After the second (same) firing the scratch was still there. I was brave and slumped it tonight and it looks fine so far. The oven is still too hot to properly open.
So I’m pretty sure it can’t be the glass. How could I alter my firing schedules? It looks pretty safe to me, lots of time for hold.