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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.


Copyright 2006 Brad Walker.  All rights reserved.

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Copyright 2005-2006 by M. Bradley Walker.  All rights reserved.

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