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Quite a few manufacturing processes involve heating the materials up real hot. In soldering, two pieces of metal are heated until a third metal melts over, wets, and bonds them. In welding, the metal to be joined is heated so hot that it melts and flows together. In glassblowing, glass is heated until it acts like the viscous liquid that (according to folklore) it always was. Etc. And when you're engaging in any of these processes, sooner or later you're going to learn -- directly and personally -- the Glassblower's Lament, namely: "Hot glass looks exactly the same as cold glass."

(In other words, you can't tell just by looking at it whether a recently-worked piece is still too hot to touch, and if you guess wrong -- Ouch!)

I swung over from the pipe soldering page.

I am a glassblower, and when the author stated that a hot pipe and running it under water could cause glassblower's lament, I predicted that he was talking about a somewhat common accident around a glass forge.

To simplify, when you blow glass, you stick a hollow tube in very hot glass, and one end gets cherry-red.

When you are done with the tube, you need to remove the remaining glass. So you shock it off with water, which cools the end rapidly, and the glass cools and cracks off.

The key is to always keep your thumb over the end you blow into.

On a regular basis, someone will be hurrying, and not remember, and suddenly they have all the water in the bucket spray upwards in a geyser thru the upright cold end, as the hot end heats the water to steam and Boyle's laws do the rest. It is 80% funny, 9% annoying, and 1% dangerous, as the water contains broken shards of cracked glass that could penetrate an eye.

Later

Cossack

cossack@spamcop.net

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