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Simultaneous Tack Fusing and Drop Ring Slumping

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 reserved.

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.

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

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