Re: [ATM] Does exposed Pyrex lose polish over time?

[Andy Saulietis <iss@pvtnetworks.net>]

Greg writes,


>If it is a combination of chemicals and dirt losely in
>contact with the surface or adsorbed to the surface
>then maybe a swabbing with conc. nitric acid ( which I
>would repeat 1 or 2x) then copius rinsing with  water
>( distilled deionized is best, followed in order of
>preference by reverse osmosis, then distilled, then
>rain water and lastly tap water).
>
>This should remove any and all films, surface
>contaminants, oils, greases and a multitude of
>inorganic materials.

I'd be a bit cautious about putting acid on mirrors..
I went thru a 6 month re-coating exercise with a 24"
commercial mirror. The coating only lasted a for weeks before
deteriorating with parts of it flaking off. Previous
coatings by the same coater had *no* problems. Several
unsuccessful efforts later (cleaning, solvents etc) we
determined that the mirror had been wrapped in newspaper
when shipped to coaters the first time, the newspaper
got wet, and leached something (probably acid of some type)
into the microcracks in the polished surface. The solution
was to return the mirror to the maker, who polished it
for a short time to seal the surface. The next coating
has lasted for at least 10 years in a very humid climate.

Take this for what it's worth...


Andy Saulietis
ISS Enterprises
10 Milky Way
Mayhill NM 88339


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