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Re: Cleaning glass
Roger S. Miller wrote:
>>Is there anyone reading that actually has credentials in
glass chemistry and would like to comment?
Anyway, this might lead to the possibility that Paul's covers were made
from an unusually soluble glass formulation and that the problem might be
avoided by using a different kind of glass.>>
Credentials? IDK, but in an earlier career segment I was responsible for
running the precision optics shop at Hewlett Packard. The solubility of
glass was a chronic PITA at that time.
Fused silica (SiO2) has pretty low solubility and high melting point. It is
not easy to work with and polish, as a result. Window glass (aquarium glass)
is often called soda-lime glass from the fluxing agents added to it. Viewed
edge-wise it has a greenish tint. It has a lower melting point and much
higher solubility than pure quartz or fused silica (crystal or fused SiO2).
Water-white glasses are much more expensive, but tend to be less soluble in
We found hot Alkinox solution, an alkaline detergent used for cleaning
glass, could easily etch the Kovar-sealing glass we needed to use for making
mirrors for lasers. Until we discovered that, we spent a couple of anxious
weeks trying to catch the sabateurs that were ruining our mirrors. :-)
"Pyrex," Crown and Flint glass were more resistant, but soda-lime glass was
just about as soluble.
Condensation is pure distilled water -- a pretty agressive solvent. I would
not doubt that over a long period it could noticeably damage the surface of
soda-lime cover glass.
Wright Huntley, Fremont CA, USA, 510 494-8679 huntleyone at home dot com
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