SO WHAT IS FUSED GLASS?

Fused glass is a term used to describe glass that has been fired (heat-processed) in a kiln at a range of high temperatures from 593º C (1100ºF) to 816º C (1500ºF). There are 3 main distinctions for temperature application and the resulting effect on the glass.

* Firing in the lower ranges of these temperatures 593º-677ºC (1100º 1250º F) is called slumping.

* Firing in the middle ranges of these temperatures 677ºC- 732ºC (1250º-1350ºF) is considered "tack fusing".

* Firing the glass at the higher spectrum of this range 732ºC -816ºC (1350º-1500ºF) is a "full fuse".

All of these techniques can be applied to one glass work in separate firings to add depth, relief and shape.

Most contemporary fusing methods involve stacking, or layering thin sheets of glass, often using different colors to create patterns or simple images.

The stack is then placed inside the kiln (which is almost always electric, but can be heated by gas or wood) and then heated through a series of ramps (rapid heating cycles) and soaks (holding the temperature at a specific point) until the separate pieces begin to bond together.

The longer the kiln is held at the maximum temperature the more thoroughly the stack will fuse, eventually softening and rounding the edges of the original shape.

Once the desired effect has been achieved at the maximum desired temperature, the kiln temperature will be brought down to avoid devitrification. It is then allowed to cool slowly over a specified time, soaking at specified temperature ranges which are essential to the annealing process. This prevents uneven cooling and breakage and produces a strong finished product.

While fused glass techniques are generally used to create glass art, glass tiles and jewelry, the slumping process allows the creation of larger, functional pieces like dishes, bowls, plates and ashtrays. Producing functional pieces generally requires 2 or more separate firings; one to fuse the glass and a second to shape it.