Have you ever noticed ugly, hazy, gray coloration around the edges of your full-fused designs? This is especially noticeable when placing darker colored or iridized glass designs on a lighter colored background but it can happen with any color combination. This phenomenon is known as edge-devit (devitrification) and is most often caused by grinding the glass edges prior to fusing. This also occurs when using a diamond blade saw to cut your glass.
One glass manufacturer explains it this way; The roughened edges in the ground area create thousands of tiny points from which crystal growth can easily propagate. The best solution is to score and break the glass as close to your final shape as possible to minimize grinding (or better yet avoid it altogether).
If you must grind you could try using a light coat of clear overglaze (i.e. Fusemaster Super Spray) on the ground areas to create a clear surface glaze.
This Randys ProTip brought to you by the book, Introduction to Glass Fusing by Petra Kaiser. Visit Wardell Publications.
Divitrification After a Full-Fuse Firing
