glass casting

New Mexico Clay’s tutorial on glass casting in a clay mold. Fire the clay mold 100 degrees hotter than you plan to use it. I fired the bottle glass to 1600 degrees @ 500 degrees/hour. So it took roughly 3 hours to reach that temperature. Then I held it at that temperature for 30 minutes. Next, I fired down as quickly as possible to 960 degrees, and annealed for 3 hours. The reason you anneal is because the glass is not uniform yet. Some areas may be hot, some may be cool. Annealing time will depend on the t