Shattering Glass Stories
(part of this continuing series)
The head of the glass department at my art school did (and probably still does) large-scale constructions and installations involving sheets of window and plate glass in various sizes. He once told our class that glass was the only material he knew of that, once it broke, a certain weight was suddenly and spectacularly taken away, so much more than with wood or metal. He recalled the inner tension of an otherwise ordinary sheet of plate glass causing it to shatter into small pieces as it was being lifted into position during one of his installation set-ups. There was a major effort to keep the pulley suspending it in midair from recoiling too much from the instant release of all that weight and shattering other sheets of glass in the process.
Shattering glass can indeed be dangerous. A student in the glass department was in the cold working shop, grinding and polishing the sharp edges of a large blown glass sphere. He was using a compressed air hose to blow out of the narrow opening of the sphere some remains of the polishing process, and was not wearing safety glasses while doing so. The explosion brought everyone then on the floor into the cold shop, and there he was, standing amongst broken shards and sporting some imbedded in his face. Many operations restored his face and his eyesight, and he returned to the glass department, eager as ever to keep doing what he loved. And we all had a hard lesson in safety and in common sense.
A fellow glass student needed to get a large amount of frit, or very small pieces of broken glass, for a fuse-casting project she wanted to do. She obtained a large piece of tempered glass for the frit, and brought it into that same cold shop for her purposes.
Everyone knows about tempered glass - and if not, suffice it to say it is now an everyday thing. The windshields of cars are tempered - that is, they are instantly cooled once they are made from hot glass, thus sealing in tension that is ready to be released, say, when an accident happens or when a good sized rock or log falls on the glass. The released tension causes the glass to explode into tiny pieces that are less likely to hurt the driver and/or passengers involved in an accident.
The student donned her safety glasses, oiled her glass cutter, and proceeded to score the glass just as I was walking past the cold shop. Her cut into the glass caused the explosion she needed to get her frit, and she was laughing somewhat maniacally when I came running in to find out if she was okay.
Finally, a mean trick. I heard about this one through a former teacher of mine. He and a good buddy of his happened to be at a summer glass school just north of Seattle at the same time Vietnam Veterans' Memorial architect, designer, and artist Maya Lin was an artist in residence. The two guys introduced Ms Lin to the Prince Rupert Drop, which is what the whole concept of tempered glass is based on. Hot glass was dripped straight from the furnace into a cold, cold bucket of water and allowed to cool. The drop was carefully pulled from the bucket - carefully pulled, I say, because the drop, when made just right, has a tail on it, and the tail is the key to releasing the tension in the drop.
The guys hit the drop with a hammer to demonstrate the strength of the instantly cooled drop. True to form, the drop didn't even chip. Then one of the guys handed the drop to Lin and asked her to hold on to it, to make a fist around it. "This won't hurt, will it?" she asked.
"Oh, no," they said, just before they snapped the tail of the drop.
My own palms smart at even the thought of this happening. Ouch, ouch, ouch. Mean, mean, mean.
And oh, what Maya Lin must think of glassblowers...