Re: ATM Additional...

[Gil Stacy <gstacy@premierweb.net>]

For what it's worth, the following is extracted from instructions
furnished by Bob Fies, a man who provides coating services in the Bay Area:
  " Beyond mirror cleaning

     Eventually the coating will become dull even with the best of care.
       It may take ten years or longer before the average person can
       notice a loss in the image.  Salty or acid air will deteriorate
       the coating sooner.  The mirror will then need to be recoated.

   Decoating in preparation for recoating may be done by Aluminum
     Coating.

     Decoating    Wash gritty dirt from the mirror.  Lightly spot polish
       the entire first surface with cerium oxide or rouge using your
       finger or a lens paper.  Hopefully this will break through the
       SiO over coating and the oxidized aluminum.  Be sure to polish
       around the edge because for some reason the coating is less 
       affected by chemicals at the edge.  Next put a solution of Drano
       on the surface or immerse in 50% concentrated HCl CuSO4 solution
       or both alternately.  CAUTION, use rubber gloves and have plenty
       of wash water available in case there is a spill.  CAUTION, do
       not allow chemicals to dry on the mirror surface.  If the mirror
       was recently coated the coating will come off entirely in about
       40 minutes in HCl solution.  On a very old coating the aluminum
       is highly oxidized and may have begun to react with the glass.
       These are difficult.  Do not leave the mirror in concentrated HCl
       overnight or the glass surface may become pitted.  Eventually a
       mirror will have to be repolished and figured due to the glass
       becoming crazed on the surface from age.

   Aluminum coating is done by Aluminum Coating in a high vacuum tank.
     Aluminum metal is evaporated from a wire near the bottom of the
       tank and coats the mirror which is being rotated at the top of
       the tank.  A very thin SiO transparent coating is coated over the
       aluminum coating.  The mirror never becomes hot.  A recoated mirror
       looks just as good as new."

   

I am not entering my dog into this fight.  I just thought this information
would be useful.

Gil Stacy, Savannah, GA