My guess is that with a deep mold, the glass will recede even if you fire it at a slower rate, or lower process temperature. However, it is impossible to do more than guess unless we know the mold style number, the cycle you used, and the size and dimensions of your glass blank.
Feel free to post again if you want to share those details!
Mary Kay Nitchie
Bullseye Glass Co.
Subscribe to Bullseye kiln-glass videos at