How Fused Glass Artglass Is Produced
Glass SelectionFused glass Artglass can be produced in a very wide range of shapes and sizes. The colors are limited only by the selection of art glass you can find. There are many manufactures of glass around. The Bullseye Glass Company manufactures most of the glass used in my studio.
The most important thing about the glass is that it must be compatible glass. All of the glass used must have the same COE (coefficient of expansion). Different glasses will expand and contract at different rates if this rate is too great stress will build up in the glass. If there is too much stress created in the glass the piece can develop fractures and can even shatter.Some glass may be not compatible even with the same COE. This is why glass manufactures must test their glass to make sure it is useable for fusing. This is also one reason why art glass is very expensive. A single sheet of glass 36" X 20" can easily cost over $100 dollars. The following companies all produce tested compatible glass Bullseye, Spectrum, Uroboros, Wasser, Gaffer, Effetre and other smaller companies.
Production of Large PlateThe first step in the production of a large plate is the selection of the glass that will be used for producing my artwork. I try to use various colors and patterns that will complement each other. Plates are most often made by stacking three separate layers of glass and then fusing them. I usually start with a colored bottom layer of glass. My next step in producing a large plate is to use a circle cutter to scratch a line into the glass sheet. You can then use controlled pressure to run a line (fracture) around the circle to pre-break the glass. You then can use a hand glass cutter to make small cuts around the glass circle to remove it from the large sheet of glass. A top sheet of clear glass is then cut out and placed on top of the bottom sheet. The round glass pieces may have small areas, which need to be removed to smooth the edges. The easiest way to remove this glass is to grind it with a diamond coated wheel. This is now your "canvas" for your design. I then start building the design for the plate. I often start the design by using interesting shapes or patterns and build from there. These shapes are cutout using a small hand cutter. Similar to the familiar glasscutter that may be used to cut window glass. This is a very individual process. Everyone will have his or her own ideas for doing this. Stained glass pattern books are a good source of designs. You can also make your own patterns from your personal photos.
Fusing piecesBefore you move your piece into the kiln you can glue the parts together using common household white glue and a toothpick. Just put a few small spots on each separate piece and let dry. This does not have to be done but can save you work if you are unsteady in loading into the kiln. If your unfired artwork has many small pieces or you need to transport it to someone else's kiln this can be especially important. Once the pieces are all cut out and arranged it is loaded into the kiln.
Slumping fused pieceIt is then heated to a temperature of around 1450 - 1500 degrees Fahrenheit. This process takes many hours to complete. There are several stages the glass must go thru. These stages are heating phase, soaking phase, rapid cooling phase, annealing phase and cooling to room temperature phase. The various times and temperatures needed are programmed into the kiln's electronic controller. This makes up what is called the firing schedule. These processes cannot be rushed or the glass can fracture now or latter due to stress buildup. Slumping the flat glass over, into or through a mold makes the shape of the piece. The molds used can be made of clay, stainless steel or other materials. The flat glass is placed on the mold and then placed into the kiln. The piece is then fired to a temperature around 1200 to 1300 degrees Fahrenheit. This is another firing schedule that takes many hours to accomplish. These firing schedules will vary depending on the type of glass used and the size and thickness of the glass piece made. Telescope mirrors can take a year or more to finish a firing schedule.
This is not a complete description of the process just the main processes. There are many good books available about glass fusing. There is also a lot of information available from the many manufactures of art glass.