Want to minimize the look of bubbles in fused pieces?
This technique used in kilnforming circles for many years has also worked well for us.
Add a light application of Clear powder between the layers with a full-fuse firing schedule. That’s right: between the layers! You’ll actually trap more bubbles, but they’ll be smaller than the usual “champagne” bubbles—and to that we say, “Cheers!”
Tip: To get an even distribution of powder, keep your sifter at least 18˝ (45 cm) above the surface and apply with multiple light taps to the handle.
The firing schedule in this article has a built-in “bubble squeeze” when the glass is in the 1200-1225°F range. The glass softens in this range and, as the layers settle, much of the air is squeezed out. We’ve tested this extensively on 6˝ × 8˝ tiles. For larger works, you may want to extend the hold time at 1225°F.
Note that the smaller bubbles created by this technique can also result in a flatter piece, whether it’s fired with transparent, opalescent, or iridized glasses.