Reducing unwanted air bubbles in fused glass projects can be achieved by incorporating a specific step into your firing cycle: a pre-rapid heat soak.
Understanding Bubble Reduction
Bubbles in fused glass often form from trapped air, gas from binders or surface contamination, or outgassing within the glass itself during heating. While complete removal can be challenging, methods exist to significantly reduce their occurrence. The pre-rapid heat soak is one such technique that leverages controlled heating to minimize trapped air pockets before the glass fully fuses.
Implementing a Pre-Rapid Heat Soak
Based on best practices in fused glass firing, a key method to lessen bubbles involves holding the kiln at a specific temperature range for a set duration before reaching full fusing temperature. This allows air trapped between glass layers or within the glass structure to escape as the glass begins to soften.
Specific Heat Soak Parameters
For effective bubble reduction, particularly in typical projects around 6 mm thick, consider adding a heat soak using the following parameters:
- Temperature Range: Hold the kiln temperature between 1150°F and 1250°F (which is equivalent to 621°C to 677°C).
- Duration: Maintain this temperature hold for 15 to 45 minutes.
These parameters can be summarized as follows:
| Parameter | Value |
|---|---|
| Phase | Pre-Rapid Heat Soak |
| Temp | 1150–1250°F (621–677°C) |
| Duration | 15–45 minutes |
| Purpose | Reduce Unwanted Air Bubbles |
| Example | Suitable for 6 mm projects |
During this heat soak, the glass will soften enough to begin moving slightly and allow trapped air to migrate out, but it will not yet have reached the full viscosity required for complete fusion. This controlled softening phase is crucial for releasing bubbles before the glass seals itself at higher temperatures.
By incorporating this pre-rapid heat soak to the firing cycle, you can significantly reduce the number of unwanted air bubbles in your fused glass creations.
