Re: ATM Silvering Techniques

[UC007@aol.com]

In a message dated 12/14/1998 8:42:00 PM Eastern Standard Time,
ohara@azstarnet.com writes:

<< (1) How many square inches of mirror surface will this batch cover?
 
 (2) What can you tell us, either first- or second-hand, about how often
 a silvered mirror will need to be redone, compared to an aluminized
 mirror? >>

(1) If memory serves, that should be enough for a 12.5" mirror. It's important
to be able to slosh (agitate) the solution evenly over the entire surface of
the mirror to assure an even coat yet without exposing any part of the mirror
surface during the process.

(2) Silver will tarnish in time. The length of time depends on what air
chemistry the silver is exposed to. If you live down wind of a fossil fuel
power plant burning high sulfur coal, the coating, even with care, will last
less than six months. If located in a dry climate away from noxious fumes, the
coating can last for many years. One thing that stands out in my mind is that
silver can be tarnished quite a bit before it loses its reflectivity
appreciably. To put it another way, silver can look dull and be bright, and
often aluminum will look bright and be dull by comparison. I got away from
silver because of my proximity to a paper manufacturing plant back in the
sixties. I guess today where I live in SW Florida, I could go back to silver
and expect a couple of good years at least.

Clear and Dark Skies,
Bill Fries, EAS