Kiln-Forming Glass at N.C. State University - Prague Institute with Benton Jones

[bentonjones]

I am not sure which pieces you are referring to. Some of the cast glass pieces have a mat appearance due to the plaster/sand molding process. Depending on the final desired outcome, firing temperatures will differ. Casting is at the highest temperatures at about 1650 F, then fusing at 1470 F, and finally slumping is done at the lowest temperatures 1250-1320 F. The type of glass used also dictates firing temperatures. Window (float) glass is higher than Bullseye (art) glass.

[FlashJack85]

Do you think you might have run the kiln a bit too hot or too long or both? Some of the pieces looked a bit over-slumped and others looked devitrified.