What is a bubble squeeze?
The term bubble squeeze refers to the process of allowing the glass to relax gradually allowing the air to escape to the edge of the piece.
The exact temperature is dependent on the softening point of the glass, its weight, and the complexity of the layup. Normally the bubble squeeze is performed with a soak of about 30 minutes at the slumping temperature.
Of course, glass being glass, the slumping point of any glass is a range temperatures. This can be taken advantage of for complex layups or potentially difficult projects. Pick the temperature about 50°C below the standard slumping point. For example, Bullseye recommend 677°C as the slumping point. Programme a slow rise - say 50°C per hour - from 625°C to 677°C where you also soak for at least 30 minutes. This slow rise allows an even more gradual and progressive relaxation of the upper glass toward the lower.
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