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SK-14 Glass

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Posted by Robert May on June 10, 2004 02:57:32 UTC

Any of the optical glasses will be better as parts of a refractor than as a mirror.
It is somewhat softer thqn plate glass and has lower abrasion resistance as well as corrosion resistance. As an optical glass it really wants to be coated on external surfaces to keep the glass clear.
I don't know if I'd really want it but at this time, something in the way of 12" diameter and 1.2" thick piece may be usefull to me if it is availble in pieces this large. I can check with my 12" scope design and see if making it a triplet with that glass included can help it do a good job.
I'll also note that if the glass has no melt index papers with it, it is worth a lot less than if there are melt index papers.
Also, if the glass isn't clear but has striae (looks like waves inside the glass) or bubbles, it is only good for cheap mirrors as the striae will cause figuring errors over time.

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