![]() and he just used a spinning steel plate that ran in this slurry mix. My great uncle was a jeweler and he had a guy in the shop who would do the cut crystal monograms on glasses for wedding gifts, retirements, etc. ![]() Sorta like valve grinding compound, only way finer, you used to be able to buy diamond dust in various grades that were then suspended in mineral oil and this was how glass engravers, or gem cutters, or MD's sharpened their scalpels, all depending on what sort of wheel was run thru the slurry. That glass wheel might just be glass, and it was run in a little pool of slurry that was the sharpening agent. Such a wheel made of saphire would look very much like glass. The oil is used to cool the knife blade so as not to destroy the temper and also to carry way the tiny bits of metal that are abraided off the blade. It would also be a good material for sharpening small knives such as scalpels. ![]() Saphire, Al2O3, is one of the hardest substances known (in the league with diamond), properly grown and polished, it's crystal-clear, and it's relatively inexpensive. Some of you are wearing a piece of it right now which has been polished and protects the face of your watch. ![]() But, it is fairly easy to make large batches of Al2O3 in a laboratory and carefully grow it into very large pieces (round pieces six inches in diameter are not uncommon). Large, naturally-occuring saphire stones are rare because the process is, as noted above, normally self-limiting. Saphire gem stones are just big pieces of aluminum rust. Once a few molecules thickness layer of rust forms on the surface of a piece of aluminum, it forms such a tight crystal structure and it's so hard that the piece of aluminum becomes encased inside of the crystal-clear rust and no more oxygen can reach the aluminum, so the rusting process stops.Īluminum oxide, Al2O3, has another name: saphire. In fact, just about every piece of aluminum you've ever seen has been completely covered with rust.īut, aluminum rust, aluminum oxide, is first) crystal clear, second) extremely hard, and third) has such a tight crystal structure that it seals the surface of the aluminum it forms on. One might object saying, "But aluminum doesn't rust! That's one of its strengths." Ah, but the fact is that aluminum does rust and it rusts almost instantly upon exposure to air. specifically aluminum rust, aluminum oxide, Al2O3. My guess is - and it's just a guess - that that "glass" wheel is not glass but is actually made of rust. My guess is that your scalpel sharpening machine was a minor product of Spinco and probably didn't survive the merger with Beckman whch means that it probably dates back to at least 1950. Today, Beckman Coulter makes some of the fastest production centrifuges in the world capable of exposing samples to over one million G force. Today, that line survives as Beckman Coulter's Spinchron line. Spinco's major products were very high-speed centrifuges, some of the fastest of their day. In the mid 1950s, Beckman acquired a company, Berkeley Scientific Corporation and Specialized Instruments Corporation, which was most known by one of its tradenames, Spinco. In the late 90s, it was spun off of Emerson and merged with Coulter Diagnostics Corporation, another manufacturer of scientific and medical laboratory aparatus. It was sold to Emerson Electric Company shortly thereafter. In the mid 80s, Beckman was acquired by SmithKline Corporation. Beckman Instruments is a major manufacturer of medical and bio-sciences equipment since about 1940.
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