About Fused Glass
Fused glass dish.
What is fused glass, anyway?
Fused glass, sometimes called kiln-formed glass, is different from the two types of glass one encounters more often in daily life—blown glass and stained glass.
Blown glass: You have probably seen televised or in-person demonstrations of people blowing hot glass. They heat it to around 2,000° F in a large pot in big ovens, then grab some onto one end of a metal pipe. The artisan blows air into the hot glob of glass from the cool end of the pipe, then shapes the resulting gooey glass globe with wooden paddles and giant tweezers, all while spinning the pipe. (Think Netflix’s competition show “Blown Away.” If you haven’t seen it, I recommend catching an episode.) Color can be added, but shape is the main characteristic—for everything from wine glasses to sculpture.
Blown glass being heated during shaping.
Stained glass uses individual pieces of flat colored glass cut into shapes at room temperature and framed by a ribbon of soft metal (often lead or zinc) that helps to connect each color into a larger image. Stained glass is commonly found in places where the play of light through glass is emphasized, like church windows and sun-catchers. It stays flat and isn’t heated. Color and translucency are the focus.
Stained glass is pieced together and held in place with soft metal edging.
Fused glass combines the best of both of these techniques to emphasize both color and shape. A fused glass artisan starts with sheets of flat glass. This glass can be translucent or opaque, clear or vibrantly colored, and can contain mixes of color or even bits of other glass. Other starting glass can have previously been heated and pulled (like taffy) as thin gooey strings or even groups of strings that will make patterns when cut in cross-section. The artisan chooses her starting materials, cuts and assembles the desired shapes, arranges everything (flat) and then heats it all in a kiln. The heating and cooling process is slow and carefully controlled, and typically follows a 5-(or more) stage program. This allows the glass pieces to heat evenly, melt, fuse into each other, anneal, then cool gradually and evenly. Once cool, the fused glass can be cold-worked which includes more cutting, grinding, sanding, sandblasting, and sometimes even drilling holes into it (carefully!) The resulting flat glass can then be placed into a mold and returned to the kiln for a process called slumping. This time the kiln program heats to a less hot final temperature: hot enough for the glass to soften and ‘slump’ into the mold but not so hot as to change the prior design.
In the kiln and ready to fuse!
Fused and cold-worked. Now back into the kiln to slump.