Re: [ATM] Removing a chrome(?) coating layer

[David Weinshenker <daze39@earthlink.net>]

Guntram Lampert wrote:
> Hi all,
> 
> A few days ago, I tried to remove a mirror coating by polishing it off 
> since I intended to do some figuring anyway.
> 
> A first layer came off pretty quickly, followed by a second one that 
> left a dark grey residue on the lap. No doubt this was the aluminium. 
> But now I am left with a metallic layer that I suspect is chromium. I 
> once read that it is used as a first layer to improve the adherence of 
> the aluminium.
> 
> Now, I can´t get rid of this first layer. Treating it with diluted 
> hydrochloric acid, no result. Added ferrous chloride solution, nothing.
> 
> Rubbed it with "soft" abrasives, remains there.
> 
> What to do?

http://www.fpi-protostar.com/secmirror-faq.htm (item 5)
suggests, for removal of such chromium base layers, a
50/50 mixture of hydrochloric acid (presumably the
full-strength solution) and glycerin.

-dave w
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