Re: [ATM] Polishing staining

[Mike Lockwood <melockwo@uiuc.edu>]

Doug,

I use the similar supplies, occasionally on plate, but usually on 
Pyrex.  My guess is that the mirror is simply not getting cleaned 
properly after polishing.

I find that a mechanical process, i.e. wiping the mirror with the side 
or palm of the hand, a paper towel, etc., is needed to completely 
remove the residue left over from polishing.

For a 6", I recommend a rinse of water, followed by a wiping with the 
hand (covering all of the surface a couple of times), then repeat that 
again.  To get it dry, I squeegee it off with my hand or a paper towel 
until no water remains, and this prevents water spots, too.

After the mirror is dry, you can use the heel or side of the hand to 
feel around the surface.  Residue typically feels "sticky" as you 
slide your hand across.  (A clean hand will not scratch the mirror, 
just avoid playing in the sandbox before you do this.)

I wonder how many mirrors have "roughness" simply because the mirror 
maker didn't get them cleaned of residue after the last figuring step? 
It's up to the optician to do this final cleaning - the coater can't 
do it safely, and it isn't the coater's job.

	Mike Lockwood

Douglas Arion wrote:
> I'm doing my bi-annual ATM class here...and having a
> problem I've seen once before that seems to be
> inexplicable: Polishing plate glass 6" blanks on Gugolz 64
> using CeO from Salem, several of the students get a thin
> filmy coating on their mirros which seems to be removable
> with acetone and hard, and I mean hard, rubbing (we're
> using surgical cotton), which does optically affect the
> glass (which is then polished out with the next session).
> Any ideas what's causing this? Was to eliminate it? Not
> everyone gets it (I have fifteen mirror makers at the
> moment), and no one who gets it sees it all the time, just
> intermittently.

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