Re: ATM removing coating

[Bill Marriott <bmarriott@pacbell.net>]

Hello;

Yes you can polish through the coating, sometimes may 'clog' up the lap,
or you can strip it, using circuit board etchant, Ferric Chloride,
available at your local electronic supply place. Since you are going to
do more polishing, you could also use liquid plumber, aka KOH (potassium
hydroxide), easier to find, but will fog the glass surface somewhat.

Either way you go, please try to remove the html formating of your
messages

Bill Marriott
http://www.starlightoptical.com
http://www.vaoptical.com


> pbunn wrote:
> 
> I have a  6" F5 mirror that was supposed to be ready for installation,
> but upon testing is spherical and needs to parabolised.
> 
> Can I make a pitch lap and begin polishing over the existing coating
> (It seems like someone on this list in the past told me this was OK)
> or must I remove the coating chemically first?
> 
> 
> Pat Bunn