How do I prevent devitrification?
There are four simple steps to preventing unwanted devitrification: Make sure that your glass is clean. (Do not use a commercial glass cleaner such as Windex, because they contain polymers that create devitrification during the fusing process. Handle your glass only by the edges once it is clean. (Use white cotton gloves to prevent the transfer of oils to the surface or edges of the glass.) Make sure that you are using a non-devitrifying surface up. Most art glasses are formulated to help prevent devitrification. When firing with float glass (window glass) place the tin side up (see tin-meter). Make sure that you are going faster than 250 degrees Fahrenheit per hour through the devitrification range (from about 1300°F to 1400°F). Be aware of thermal mass if you have an underpowered kiln, if you are kiln casting large objects, and/or if you have multiple shelves in a side fired kiln. Use Fusing Farm Freedom Flux as an anti-devitrification surface modifier.
