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Just Say No To BVC

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Posted by Rick Crockett on August 10, 2000 05:29:33 UTC

I have yet to find anyone making large mirrors with BVC that were happy with the product. While a little bitty 6 or 8" might work OK, several that I know of have been very unhappy with the larger blanks. If you shop, Pyrex can be found for less in all sizes. Certainly the 24" x 2"T for $900 is no bargain.

I understand the coater may have a fiducial relationship with ASM. Even if not, what does a coater know? Very little. Now if a professional mirror maker used the product that would be something. Do you think there might be a reason none risk their good name?

I would make a mirror out of plate glass for half the price and certainly a more reliable and predictable material. I would not waste my time with a BVC blank even if it were free.

BVC despite what they call it is a course ceramic, not glass. It is vitrified to make it glass like but then it is not homogenous and part ceramic and part vitrified? Do not mistake the quality with ceramitized glass which is run through annealing and re-heating cycles for weeks to obtain zero co-efficient of expansion. To make such a comparision is a poor joke.

I have seen a telescope made out of Black Granite. Other than the novelty why do it.

Gerry, I hope you continue to be satisfied with the product but I suspect you will not as you start into the larger sizes. Good luck Though.

Just say No to BVC

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