Kiln-Formed Glass
 Since you might not be familiar with kiln formed, or “hot”, glass, I thought it might be useful to provide a brief description of the medium and the process of its making. Firstly, though it shares a few characteristics in common with each, the method of crafting kiln formed glass is quite unlike both mouth-blown and molded glass. The pieces are not made from batches of molten glass but are, rather, fabricated from sheet glass that is first cut and ground to shape on a diamond wheel. In this respect, the process is more akin to stained glass techniques with which I am more intimately familiar.
The cut pieces, once assembled, are fired in a specially designed kiln to a molten or nearly molten state (usually between 1350 and 1550 degrees Fahrenheit, depending on the desired effect and the nature of the variety of glass utilized) so that they are fused together. Only specifically formulated glass that has been tested to have a compatible COE (coefficient of expansion) can be fused together in the same piece. Conventional stained glass can also be used, but it can only be fused to itself. In addition to the cut pieces of sheet glass, decoration also can be applied using enamels (glass ground to a fine powder, which is permanently fused to the base glass), glass “frit”, “stringers” and “noodles”, metallic powders, powdered mica and metal leaf or foil.
 The final stage of the process is to manipulate the fused glass “blank” into the desired shape. This is accomplished using a variety of molds, forms or drop rings. The piece is “slumped” into, over or through one of these forms by again firing it in the kiln, but at a somewhat lower temperature than the fusing stage. Most pieces require two or three kiln firings, ranging from about 13 to 17 hours each, since kiln-fired pieces must also undergo annealing and slow-cooling cycles in order to avoid cracking due to thermal shock, which occasionally occurs even when precautions are taken to prevent it.
I should also note that kiln-fired glass pieces cannot be stacked, as in ceramic kilns. In smaller kilns, such as the one I use, only one piece, generally, can be fired at a time. Unlike blown glass, which, of necessity, is worked quickly, this process typically requires from 3 to 5 days to make just one piece. More complex pieces may take considerably longer. In addition to being time-consuming, it is also an expensive medium, not only in material costs but also in energy consumption. I mention this in the hope that you will understand that these pieces must be priced in accord with these factors. I hope you will also appreciate that, though a few patterns can be replicated, more or less, these are unique pieces of art glass, not mass-manufactured production items. For me, the design and hand-craftsmanship are at least as important as in a painting or any other piece of artwork.
No doubt you will observe that this work exhibits many of the quirks and variations that are characteristic of handmade glass. This, I hope you will agree, is part of its charm. Much of the sheet glass I use is also handmade, notably that produced by the Youghiogheny, Bullseye, Wasser and Uroboros glass works. In this regard, I should mention that the glass produced by Youghiogheny Glass, both fusible and stained, is an excellent world-class resource of exceptional quality, and it is made locally in Connellsville, PA. These various styles of handmade glass often contribute their own, often unpredictable, eccentricities.
|
