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Preventing Uneven Bowl Slumping


One of the problems that sometimes occurs when slumping bowls is that the bowl will slump unevenly, with one edge slightly higher than the other.  This problem is especially likely when slumping large pieces or when the edges on the item being slumped rest inside the mold, rather than on the top edge of the mold.


Here are some suggestions on preventing this problem.


1.  First, make certain that your kiln is level.  But don't stop there.  Also make certain that the mold is level on the kiln shelf.  If you start out with an uneven mold or kiln, then the results are likely to be uneven, too.  If you don't have one, get a small level that can fit inside the mold to help you do the checking.  (But don't forget to remove the level before firing!)


2.  Don't forget to check that the holes in the bottom are clear.  If they're blocked with dried kiln wash, open them up again with a straightened paper clip or similar small wire (even a glass stringer can work).  If the mold isn't propped up on kin furniture or designed to allow for air flow, that can block the holes, too.  It's important to keep the holes open.  This will help with air flow around the mold, and will also help the blank slump more evenly.


3.  If you're slumping a large, heavy item (like a sink inside a large wok), then carefully place the blank into the mold.  Use a glass suction cup if you have one.  If you don't have a suction cup to lift the item, try using the suction cup on the end of a circle cutter.  Gently lower the blank into place, then measure around the edges in three or four places to ensure that the blank is equidistant from the top of the mold. 


Click here for more tips on preventing uneven bowl slumping.


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

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