Can I fire glass and metal at the same time? I would like to combine the 2 in 1 piece.
Yes, you can co-fire metal clay and glass in a kiln. When working with the two materials, metal clay and glass, the lower firing temperature clays tend to be best, as a higher firing temperature would alter the glass. For lower firing temperatures and use with glass and other items which might be affected at higher temperature, PMC3™ or Art Clay® Silver 650 are both good choices of metal clay.
Depending on the type of clay and glass you are working with, the firing temperature and schedule will vary. An average time and temperature would be 45 minutes at 1110 to 1200 degrees Fahrenheit. At this temperature range the two materials will not fuse. A secure mechanical connection should be part of your design, such as a bezel, prongs or overlapping pieces of clay. If using a type of metal clay that requires a higher temperature, 1470 degrees Fahrenheit is still a suitable temperature, but at this range the glass may melt slightly and the two materials may fuse together. Even if there is fusing, it is still recommended to use a mechanical bond so your glass remains securely in place.
There are some important things to remember when co-firing metal clay and glass. Protect your kiln shelf by lining it with kiln paper since glass will fuse to an unlined shelf. Use a clean, dry cotton swab to remove any metal clay dust from the glass as it may fuse to the glass when fired. Venting your kiln is necessary so that the metal clay fumes do not affect the surface of the glass. Once the piece is fired, annealing the glass is critical. Annealing glass is the process of heating and cooling in a controlled manner. After firing, you can allow the kiln to cool to room temperature overnight or vent the kiln until it drops to 1000 degrees Fahrenheit, then close the door and do not open it again until it has reached room temperature. If your glass cools too quickly, stress will build up and at some point, the glass will crack.