Re: [ATM] Mirror Silvering

[waldo kitty <wkitty42@alltel.net>]

Che Ers wrote:
> I had a piece of glass silvered from a commercial mirror-maker,
> [as an experiment], but the coating began to corrode almost immediately.
> So how does the silvering done on telescope mirrors escape corrosion,
> even for some time?

they don't... a slivered mirror generally has to be re-silvered each season but 
this also depends on how well it is taken care of... there is a way to make a 
cloth that contains a mineral or herb that helps to protect silvered mirrors but 
it can't protect them completely... even with the cloth, regular re-silvering is 
necessary...

how was it slivered? that may be as important as why it is corroding seemingly 
fast...

i remember my mother having a silver tea service and tableware... it stayed in a 
special box and she still had to clean and polish it before it was used but 
those occasions came about only once in a "blue moon"...

as others have and no doubt will mention, aluminizing is more common, easier to 
maintain, and last longer... the reflectivity difference is not all that much 
lower than silver, either... if you were to look thru two identical scopes, 
sitting side by side, trained on the same object, with one being a silvered 
mirror and the other being aluminized, it is highly doubtful that your eye would 
be able to tell the difference ;)

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