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Fire polishing
Fire polishing is the simple technique of returning glass
items to the kiln to melt them just enough to give a smooth,
polished appearance. It typically takes place at a temperature
that ranges from 1300 F/700 C to 1400 F/760 C.
For best results, fire polishing should take place after
fusing and before slumping. It's usually a good idea to
fuse your project, then grind or shape the edges, then fire
polish to restore the shine and round the edges. If
desired, a slump firing should follow the fire polish firing.
While it's sometimes possible to fire polish and slump at
the same time, this is a risky technique. It's almost
always best to fire polish in a separate firing that takes place
after fusing and before slumping. If you must try to fire
polish and slump at the same time, it's essential that you watch
the piece very careful to prevent over-firing. Since the
correct temperature for polishing is slightly above the
preferred range for slumping, it takes a very careful eye to
accomplish both at the same time.
For similar reasons, re-firing already slumped items to
make then shine again rarely succeeds. You're much more likely
to distort the piece by over-firing than you are to successfully
fire polish an already slumped item. Clean up your edges
and your top surface after fusing, fire polish if needed, then
slump. Never wait until after slumping to clean up the
edges and top surface of your piece -- that's almost always too
late.
Alternatives to fire polishing include
acid polishing, which can present a health hazard, and
cold working, which often requires
specialized equipment.
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Copyright 2006 Brad Walker. All rights
reserved.
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