Quick Tip: Fix Surface Flaws | Kilnforming

Quick Tip: Fix Surface Flaws


devitrified glass, repaired with use of bullseye frit powder


The growth of crystals on glass, aka devitrification, aka devit, is not that common or easy to create. But if devit does appear on your fired glass, there are several ways to remove it. One simple way, for glass that's flat, is to sift a very thin layer of Clear powder (2 grains thick) over the entire piece until the surface appears white. Then re-fire at 1425°-1450°F (774°-788°C) for about ten minutes, depending on the kiln and thickness of the glass. The resulting piece, like our tile on the right, will have a clean appearance. This method is similar to working with overglazes, but Clear powder has advantages: it contains no lead, it fires quickly, and a very small amount will get the job done.

To learn more about devitrification see:

Revised April 25, 2014.

Downloadable PDF
Quick Tip: Fix Surface Flaws

Helpful Resources

Video lesson: Firing: Basic Principles
Video lesson: Clear Powder on Iridescent Sheet Glass
TechNotes 4: Heat and Glass