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Hi- Newbie here. Hoping someone can help me understand why my glass exploded when trying to make a pocket vase. I used a piece of 1" fiber board as the form for the pocket. Using Bulleye 90 COE. I have a Paragon QuickKiln 6 with a controller. I set the controller @ 1.5 and after 10 min I heard the distinctive sound of glass cracking. Suggestions/ words of wisdom to overcome this boo- boo?
thanks!

Fiber board is an insulator. It looks like you heated up to a point where the temperature gradient within one piece of the glass was great enough to cause a thermal shock crack.

thanks so much for the fast response. I'll try using fiber paper next time.

fiber paper is an insulator too. you have to slow way down on those vases. also annealing needs to be longer. rosanna