ATM stripping mirrors

[Al Misiuk <amisiuk@wescospec.com>]

Hi,
I will strip mirrors as quickly as possible. Pyrex is somewhat more
resistant, but can still be damaged.

Ferric Chloride does well stripping aluminum, but can damage some glasses if
left on too long. Hydrochloric acid strips aluminum well also, but will
damage certain glass if left on too long. I sometimes have used Sulfuric
acid. I place enough water to cover the mirror by about 1/2 inch and slowly
pour the acid over the mirror. The reaction can be very strong, so one must
wear safety glasses and rubber gloves. It seems to do no damage to glass,
though.

New coatings are fairly easy to strip, but old coatings are very difficult
and may result with glass damage, no matter what technique is used. The
reason is that the aluminum and glass molecules had time to migrate one to
another. Stripping some of these mirrors may leave a cloudy surface,
requiring polishing and refiguring.

Al M