Slumping Fusing Glass In
A Glass Slumping Mold
Slumping fusing glass is the process of shaping glass in or over a glass fusing mold.
Two or more pieces of glass are normally heated and fused together to form one piece of glass.
This usually results in a flat piece of glass which can then be slumped in a glass kiln.
The fused glass piece is placed in a kiln washed mold and heated in a fusing glass kiln until it slumps down into the slumping mold and takes on the shape of the mold.
Slumping results in a shape such as a plate, bowl, or some other three dimensional shape.
Some simple projects may enable fusing and slumping to be carried out at the same time.
Normally two steps are required, fuse first, then slump the fused blank into the glass fusing mold.
Fusing glass is fused at a higher temperature than the temperature needed to slump the same glass.
If a piece is first slumped and then fused, the higher fusing temperature will result in the glass losing its slumped shape.
Trying to fuse and slump multiple pieces of glass at the same time will result in the glass altering shape and becoming distorted.
A fused glass piece should be cold worked to remove any imperfections before slumping.
Whenever possible faults should be removed prior to slumping as it may prove impossible to cold work the slumped glass completely.
It is very important to select an appropriate slumping schedule to ensure that that the glass is heated and cooled properly.
Slumping schedules can be found at glass manufacturers web sites. A search of the web will result in a number of glass slumping schedules.
The thicker the glass the slower the temperature increase should be. If a glass piece has been fired a number of times the slower it should be fired.
Most glass items will not need to slump at a temperature higher than 1300° F (704° C). Slumping at this temperature should result in a smooth slump.
Slumping at a high temperature may result in the glass picking up kiln wash from the mold.
The glass should be fired until it slumps down into the mold. It won't hurt to hold the glass at slumping temperature for a few minutes.
Some deep molds with sloping sides may need to be held longer.
Once slumped the glass should be cooled and annealed in accordance with the slumping schedule.
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