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.

2 comments

  1. Note to self for future: don't try to slump fancy boro colors. I haven't even tried that with soft yet (& those halves r really piling up!)

  2. Note to self for future: don't try to slump fancy boro colors. I haven't even tried that with soft yet (& those halves r really piling up!)

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