On Sunday, April 05, 2009 08:46, Chuck Norcutt wrote:
Thanks Chuck you told me what I wanted to know
> Modern first surface mirrors are tougher than most people realize. They
> are aluminized in a vacuum chamber by sputtering aluminum vapor onto the
> surface to form a thin coating. As soon as the aluminum is exposed to
> air the surface oxidizes to form a microscopically thin coating of
> aluminum oxide.
I hadn't thought about the aluminum oxidizing, but should have. I was
concerned about cleaners attacking it chemically. When you mention aluminum
oxide It's likely tougher than a lens coating. I think I may use rubbing
alcohol because that is what I have.
> You might recognize aluminum oxide as the stuff that
> grinding wheels are made of. So, while in an extremely thin layer, it's
> also very hard. It should easily stand up to any cleaning solution you
> might reasonably use on any other bit of optics.
>
> I think John Hermanson has spoken here of using bird feathers as a
> sweep. But I have none such. :-)
There was a road killed goose down the road the other day, but gone now.
Our cat hasn't caught one of the starlings despite a great desire to do so,
nor has the neighbors beagle.
--
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