What Is Fused Glass?Fused glass is generally two or more layers of glass of a specific type assembled to form a pattern. The first, or bottom, layer is a single sheet of glass, either clear or (usually) opaque. The second, or top layer is composed of pieces of glass of various sizes which have been cut from a large sheet. These pieces may be of many different colors and types of glass (transparent, opaque, iridized, etc.) The only requirement is that they all have the same coefficient of expansion. If one tries to combine glasses that have different coefficients of expansion there will be major cracking, not to mention explosion, because of stresses created by differing rates of expansion/shrinkage. My glass of choice is Bullseye COE 90.
The pieces are cut from a large sheet and assembled so that they fit closely with the neighboring pieces. The two layers are assembled, placed very carefully on a kiln shelf and fired to about 1480 degrees F. so that they fuse into one piece of glass. After this piece has annealed and cooled to room temperature, it is placed on a ceramic mold and refired to a lower temperature until it relaxes and “slumps” into the form of the mold. The piece is once again annealed and cooled slowly to room temperature.
There are variations on this process, using glass frit (coarse powder), “strings” or rods of glass, very thin shards, and other forms of glass, all of which result in different effects. The possibilities of this medium are infinite.
Fusing glass in a classroom environment or home studio only became possible with the advent of the computer controller made for small kilns, so it is a relatively new art for the general public.
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