Simultaneous Tack Fusing and Drop Ring
This is part two of
a two part series on simultaneous tack fusing and drop ring
slumping. Click here to go
to part one.
One firing schedule that works well for Bullseye glass is to start
with a rate of temperature rise of 500F/260C. Once the temperature
reaches 1250F/675C, soak for 45 minutes. This will help the layers on
top to solidly tack fuse. After the soak, heat again (you may
go as fast as your kiln allows) until the temperature reaches
1380F/750C. Now start watching the piece – it should take ten to
twenty minutes for the drop ring slump to complete. The hold
time will vary with the color of the glass. Watch carefully, at
this temperature the glass can move fairly quickly.
Once the piece has slumped the way you’d like, cool and
anneal as in the basic firing. Note also that if you’re using a
glass other than Bullseye, you’ll need to adjust the firing
schedule accordingly. System 96 glass generally slumps at about
50F/10C lower, while float glass requires temperatures that
are 50 to 100F (10 to 40C) degrees hotter. Also, because of the prolonged
time that the glass may spend above 1300F/700C, it may be a good idea
to apply an overglaze to prevent devitrification, especially if
you’re using float glass or art glass that has not been treated
to minimize devit.
The Warm Glass Gallery has an example of a piece that has been
simultaneously slumped and tack fused. Note that this piece is
displayed using a custom made metal stand.
Copyright 2006 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.