This is part two of
a two part tip on firing the drop ring. Click here to go
to part one.
- Now you're ready to fire. The
heating portion of the firing is similar to many other
firings. Just fire no faster than around 500F per hour
until the temperature reaches around 1250F. You can go
as high as 1350F if you wish, but realize that higher
temperatures mean faster slumps and less control.
Also, different brands of glass (and even different colors!)
will slump at different temperatures. As a general
rule, System 96 glass slumps at a slightly lower temperature
than Bullseye glass, and window (or float) glass slumps at a
higher temperature. But you may need to experiment a bit
to find the temperature that works best for your glass and
- Now comes the fun part. Maintain
your kiln's temperature so that the heat can do its magic.
As the glass soaks, you'll first notice a small bulge of
glass poking through the hole in the ring. As the
glass continues to soak, more and more of the glass will
poke through. Keep a careful eye on the glass as it
- It may take as much as half an hour
for the glass to droop far enough to touch the kiln shelf
below. Once it touches, you will need to continue to monitor
the glass until the base takes on the desired shape. Be
careful not to over fire or the base of the glass will
- Once you are happy with the appearance
of the piece, flash vent to stop the slumping and then
anneal and cool as normal. (Flash vent means to
carefully open the door or lid of your kiln to allow some
heat to escape. Allow the kiln to cool below 1100F.)
Remember to adjust your annealing schedule if your piece has
more layers of glass than in your typical firing.
This kind of slump is fairly simple, but
many people find the "top hat" shape appealing. It can be
varied in several ways, but it's the foundation to more
complicated shapes and drop ring techniques.
Click here to go to the
next part of this tip, which explains how to tack fuse and slump
through a drop ring at the same time.
Copyright 2005 Brad Walker. All rights
Parts of this discussion
have been previously published in Glass Craftsman
magazine. More advanced drop ring techniques, such as tack
fusing and slumping in one firing, making custom drop rings, and
creating rimless vases and bowls drop rings, will be discussed
in future daily tips.