The Great Cabochon Experiment

I was told sev­eral years ago that if you have round beads that have bro­ken in half due to ther­mal shock, you can use your kiln to slump them down into lit­tle oval cabo­chons and thereby make use of oth­er­wise wasted glass. This cer­tainly appealed to me, being one to not waste any­thing. I mean, other peo­ple have nubs and shorts of glass that they are always try­ing to get rid of, but MY shorts get used up until there’s essen­tially noth­ing left.

Of course, the peo­ple that have slumped their beads were doing it with “soft” glass, aka COE 104 Effetre/Moretti/Vetrofond glass. Did that stop me from try­ing it with my poor borosil­i­cate bead halves?

My first attempt was in my own kiln, which wouldn’t get above 1700 degrees. That isn’t hot enough to slump boro. Although the lit­tle bead halves looked a tiny bit flat­ter and more pol­ished, they still had their lit­tle grooves on the backside.

Then I took them over to my par­ents’ house to use the big guns, er, kiln (my mom’s pot­tery kiln) on them. I was fig­ur­ing what the hell, let’s give it a shot, so I set it to ramp up to 2000 degrees and let ‘er go. Four hours later, that kiln had topped out around 1930 degrees, and I had no clue whether the beads were slump­ing or not. I said to hell with it and cut off the con­troller to let them cool down overnight.

When I went back and pulled them out the next day, they were def­i­nitely slumped into nicely shaped cabs…but almost all of them had turned from their nice bright boro col­ors to a cloudy yel­low!! Dismay!!!

Accord­ing to my friend Jo, that was the sil­ver in the boro color react­ing at such a high tem­per­a­ture with the clear, and there is noth­ing to be done at that point. I still ran the cabs through the kiln one more time on my nor­mal boro strik­ing cycle, which may have helped a few of them, but most remained that cloudy baby-poop yellow.

Con­clu­sion? EPIC FAIL.