Want to minimize the look of bubbles in fused pieces? Here’s a technique—used in kilnforming circles for many years—that’s also worked well for us.
Add a light application of Clear powder between the layers with a modified 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 inches (45 cm) above the surface and apply with multiple light taps to the handle.
Modified Firing Schedule
Note that the glass reaches full-fuse temperature in a different way with this cycle. Specifically, you fire more slowly through the 1200°F to 1250°F temperature range than in a standard full fuse. The glass softens in this range and, as the layers settle, the air is squeezed out. Then the schedule moves on to a full fuse. We’ve tested this extensively on 6" x 8" tiles. For larger works, you may want to extend the hold time at 1250°F.
Angelita Surmon, Oak Island Reflections (detail), 8 x 12 x .25 inches, 2012. Surmon uses a variation of this bubble control technique to draw attention to imagery and quiet the negative spaces in her kilnformed landscape works.