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Large Air Bubbles


Probably the most common question asked on the Warm Glass bulletin board deals with the problem of large air bubbles trapped beneath layers of fused glass.  These bubbles, which tend to be around two to three inches across, occur in larger pieces of fused glass (not in small jewelry or coaster items), and they first emerge at fusing temperatures (above 1400F/760C).  


Large air bubbles sometimes expand so far that they pop through the top surface of the glass.  When this happens, the popping creates a large hole in the glass being fused, effectively ruining the piece. 


Because large bubbles are most likely to form in pieces fired on kiln-washed surfaces, firing on fiber paper will almost always prevent the problem.  However, this solution has limitations of its own -- the back of the piece isn't as smooth, and it's more costly than simply kiln washing the shelf.  Moreover, it only works for traditional fiber paper; it is still possible for bubbles to form when firing over Bullseye's thinfire paper.


The next portion of this tip will discuss other solutions for eliminating the large bubble problem.



Copyright 2007 Brad Walker.  All rights reserved.

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

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