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Old 11-05-2003, 07:36 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 22,269
Pete VanderLaan is on a distinguished road
If you want really nice glass it is probably going to contain either potash which gives lustre or barium for brightness and neither is cheap. It is not going to contain spars which are very cheap.
As to price, it probably will be cheaper from Lewis. Dave quotes 72 cents lb for potash and I pay 50. I buy a lot more. Silica should really be about 13 cents in bags and is dirt cheap in 1 ton cloth baggies. I think the difference is that you know where everything came from- you made it- and that is power.

I use SP87 for a clear when I am working it with colored glasses. I would not use it as a stand alone clear and would make either the formula Dave has listed that I wrote almost thirty years back, or a very nice 11% lead glass I pull out for special occasions. The glass should be appropriate to the project.

Just remember, get a good scale, a very good scale. I have two and I cross check every time.
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