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
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
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
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.