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Preventing Uneven Bowl Slumping


This is part two of a multi-part tip. Click here to go to part one.


Continuing the list of suggestions to help prevent uneven bowl slumping:


4.  Firing too quickly is a common reason for slumps to fail.  This is especially true at temperatures above around 1050F/565C.  Rather than increase the temperature rapidly, it's better to soak for a while around 1100F/600C, then slowly increase the temperature and then soak at your final slumping temperature.  Firing too quickly will often cause the slump to move too quickly, resulting in an uneven slump.


5.  A related tip is to slump at as low a temperature as possible.  As your final slump temperature increases, the likelihood of an uneven slump also increases.  Try to always slump below 1300F/700C; below 1250F/675C is even better.  If you fire too high, the glass can slide down the sides of the mold (especially a steep mold) and ruin the slump.


6.  Still another potential firing issue that can cause uneven bowl slumping is soaking for too long at your final temperature.  This won't be a problem with a fairly flat mold, but it can be problematical if your mold has steep sides.  Soak for as long as you need to finish the slump, but not any longer -- otherwise, you run the same kind of risks as firing too high. 


Coming soon -- more tips on how to prevent an uneven slump, as well as tips on what to do if your slump fails and despite all your efforts you create an uneven bowl.


Copyright 2005 Brad Walker.  All rights reserved.

Based on suggestions and posts from the Warm Glass bulletin board, especially from Phil Hoppes, Bert Weiss, Brock Craig.

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