soldering fused pieces

[bjames]

Hi! First-time poster, long-time lurker.
I was wondering if there are any special tricks to soldering fused pieces into a stained glass panel. So far, I've copper foiled the sides of the pieces and soldered them into the panel, and 2 out of 5 pieces suffered cracks thanks to the heat of the soldering process.
I kiln cast the pieces in a mold using Bullseye frit, and they are fairly flat and about 1/2" thick. I was very careful in the annealing process and slowly cooled the pieces in the kiln, so I don't think that this is the problem.
I've never cracked any other types of glass with my soldering technique, so I'm wondering what the problem might be. Should I just back waaay off on the rheostat and be extra conservative with soldering each piece? Any other tricks?

[Mira]

Make sure you're not soldering out in the cold, which will cause the glass to change temps quickly. Also, dont solder all the way around an entire piece at once. Do a side, solder something else, then do another side. This will allow it time to cool off a little.

Good luck.

[Marty]

I sometimes would solder with a damp cloth underneath the panel, it seemed to draw heat away from the work better. It didn't work all the time. I tried drawing a fast bead of solder and not going back over the line too much. Try keeping the iron off the glass. What about a smaller tip? Turning the rheostat down is only going to prolong the time you spend in a given spot, and the temp differential of 100 or 150 degrees won't make much difference re thermal shocking. Can you use lead came instead of foil for those pieces? You could get really sneaky and glue the piece in and cover the seam with that (ugh!) overlay tape.

That's partly why I gave up stained for fused!

[starchimes (Andrea)]

I solder alot of my fused glass. I haven't had this happen. Are you taking the frit to full fuse? If it's possible, maybe you could use clear as a base. I think maybe it has something to do with using frit?