[ATM] Coating damage from tissue paper/bubblewrap

[Mark Cowan <toolontop@yahoo.com>]

Hi All:

Received a 12.5" thin pyrex mirror today for
refiguring, it was wrapped in 51x66cm tissue paper
(American Greetings Corp) and thence in large (1" or
so size bubbles) bubble wrap and tightly secured with
masking tape.  I think it was packed that way for at
least a couple weeks, possibly longer.

Anyway, the coating orginally showed a strong pattern
of specks outlining the imprint of the bubble wrap
under foucault.  I cleaned it - or tried to clean it -
a couple times, first with soap and water, which at
least made the mirror readable, and then with acetone
wipe followed by isopropyl and distilled water rinse. 
Still showed speckles all over.  This mirror was
expected to be stripped so I was aggressive in
cleaning and did find lots of pinholes afterwards but
didn't check that first.

Anyway, on to stripping with ferric chloride, and
after maybe 10 minutes in the garage - you could
/easily/ see the bubblewrap pattern where the coating
was going away!

I think the moral is pretty clear - tissue paper
that's intended for package wrapping should not be
used on mirrors!!  There are grades (Kimberly Clark
makes some and Edmunds sells them, but not in any
large sizes) that are intended for optics and would be
safe.  But the damage done by the couple weeks (or
more) contact was severe and permanent - if this
mirror wasn't going to be refigured the coating would
have to be redone.

Cheers,
Mark Cowan
Sweltering in Salem, OR


		
__________________________________
Do you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
http://promotions.yahoo.com/new_mail
_______________________________________________
ATM mailing list http://www.atmlist.net/