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.
Since the 1970s, more hobbyists have focused on using kiln-fused glass to make beads and components for jewelry. This has become especially popular since the introduction of glass manufactured for the specific purpose of fusing in a kiln.
Thursday, February 7, 2008
Techniques
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.
This cooling takes place normally for a period of 10-12 hours in 3 stages.
The first stage- the rapid cool period is meant to place the glass into the upper end of the annealing range 516ºC (960º). The second stage- the anneal soak at 516ºC (960ºF) is meant to equalize the temperature at the core and the surface of the glass at 516ºC (960ºF) relieving the stress between those areas. The last stage, once all areas have had time to reach a consistent temperature, is the final journey to room temperature. The kiln is slowly brought down over the course of 2 hours to 371º C (700ºF), soaked for 2 hours at 371º C (700ºF), down again to 260ºC (500ºF) which ends the firing schedule. The glass will remain in the unopened kiln until the pyrometer reads room temperature.
Note that these temperatures are not hard and fast rules. Depending on the kiln, the size of the project, the number of layers, the desired finished look, and even the brand of glass, ramp and soak temperatures and times may vary.
This cooling takes place normally for a period of 10-12 hours in 3 stages.
The first stage- the rapid cool period is meant to place the glass into the upper end of the annealing range 516ºC (960º). The second stage- the anneal soak at 516ºC (960ºF) is meant to equalize the temperature at the core and the surface of the glass at 516ºC (960ºF) relieving the stress between those areas. The last stage, once all areas have had time to reach a consistent temperature, is the final journey to room temperature. The kiln is slowly brought down over the course of 2 hours to 371º C (700ºF), soaked for 2 hours at 371º C (700ºF), down again to 260ºC (500ºF) which ends the firing schedule. The glass will remain in the unopened kiln until the pyrometer reads room temperature.
Note that these temperatures are not hard and fast rules. Depending on the kiln, the size of the project, the number of layers, the desired finished look, and even the brand of glass, ramp and soak temperatures and times may vary.
Glass fusing is the technique used to join glass pieces together by partly melting the glass using high temperatures. The heating is commonly undertaken in an electric kiln. Instead of fitting glass together using a lead solder, two or more pieces of glass are laid on top of or overlapped on each other and are fired at temperatures ranging from 1100 to 1600 degrees Fahrenheit (750 to 850 degrees Celsius). It is important to realize that glasses with different coefficients of expansion cannot be fused together - upon cooling or after a certain period of time, the fused piece will crack. Many people who work in glass fusing restrict themselves to one brand of glass (e.g. Bullseye, Uroborus, Baoli) which is guaranteed to be compatible with any other glass from the range of fusible glass offered by that particular maker.
Fusing is becoming a more and more popular technique, and it allows for a very exact planning of different colors within a piece. This method can be used for intricate stained glass windows. It also can be used with paints. Miriam diFiori from Italy is a master of this technique. Often, the initial product - a flat slab of glass - is fired a second, third, or even fourth time to form a three dimensional shape.
Glass, when made hot, can be formed in a process called slumping. This is done by heating a pane of glass to the point at which gravity pulls the glass into the form of the mold that the pane has been placed. This process can be used to make plates and bowls, among other things.
Fusing is becoming a more and more popular technique, and it allows for a very exact planning of different colors within a piece. This method can be used for intricate stained glass windows. It also can be used with paints. Miriam diFiori from Italy is a master of this technique. Often, the initial product - a flat slab of glass - is fired a second, third, or even fourth time to form a three dimensional shape.
Glass, when made hot, can be formed in a process called slumping. This is done by heating a pane of glass to the point at which gravity pulls the glass into the form of the mold that the pane has been placed. This process can be used to make plates and bowls, among other things.
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