From: 
To: "steve desfosses" ,"liste
atm" 
Reply-To: 


 True, too fast and probably made indents into your mirror surface.
In optical coating terms, failure, disaster.

The fix before it was coated was open the shutter about 5 to 10 seconds
later and let the aluminum "wet" the boat.

Only thing you can do is live with it ( you probably won't see it anyway )
You can inspect with a microscope after wiping clean the mirror and if some
of the spatter coating comes off check to see if an indent is where the
mark was.

Be careful, you will most likely drag a chunk of aluminum across the
surface, do this under running water very slowly.

P.S. I noticed some sites mention chrome undercoat. This material has the
most stress of all materials and will deform a mirror surface.
Aluminum will stick properly to a clean glass surface with no help from
this undercoat of chrome.

My 2 cents, please no flames just facts.

Peter Nance, Jr.
lenses{at}adelphia.net


> From: "steve desfosses" 
> Date: 2003/07/23 Wed PM 03:28:58 PDT
> To: "liste atm" 
> Subject: ATM spatter marks on a fresh new coating...
>
> hi everyone,
> today i received my 12.5" mirror from the coater (moonward vaccum
coating) a
mirror that i have finished a month ago.so it is not a recoating of an old
one.when i was doing my little inspection of the coating i noticed a lot of
"bubble-like" spots on the surface.Ididn't count,but there is a
dozen, maybe more of them. the bigest ones seems nearly 1mm across.
> I have written to the coater and he call these "spatter
marks". He say that
it is only cosmetical and it is a sign that the aluminum was evaporated
quickly and with good durability.

I don't know what to do with this... it is frustrating to look at a mirror
and see those marks when you know you've work so carefully not to leave any
scrath, or pinhole...
> has anyone ever experienced this on an aluminum coating?
> thanks for your help...
> steve desfosses
>
>

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