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Old 11-17-2019, 11:11 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
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Join Date: Apr 2002
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To expand on the cost:

SP87 is about .80lb. The cost of cobalt oxide is about $16.00 per pound.
In 10 pounds of SP87 you'sll get about 8.5 lbs of glass and if you add 3 grams of cobalt oxide to that, you'll get an intense blue that can be cased in clear.
One lb is 454 grams. 3 grams is about 1/ 150th of a pound or around .10 per gram. Those are rough numbers. The point there is that the material costs on the colored glass are under a buck a pound and it includes the cost of the clear which you would have paid for anyways. Similar stuff can be done with copper oxide, making a very nice turquoise blue, manganese makes an OK purple. These are all simple colors but if you looked at copper rubies and silver opals , they can be made using SP color base a, bit of black tin, some zinc and some copper or silver , all quite reasonably.
Some coloring is indeed touchy. Cadmium selenium colors need good vents, gold does need some lead. Fluorines are caustic but also very manageable. You have to melt them in gas units.

The kiln can be a ceramic kiln which I dislike because of the oxidation but that can be worked around. You don't have to get crucibles from me, you could go to coorstek for cheap assay pots. You don't have to run the kiln all the time although I do since it speeds up so much stuff to have the color molten.
I wrote this entire thing up in GlassnotesIV. It's right there. Some have suggested I won't give up the formulas. I don't need to in many instances. They're already in print. I put many of them there.
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