aemeijers wrote:
Oren wrote:
On Thu, 29 Jul 2010 12:41:34 -0700 (PDT), DerbyDad03
wrote:

On Jul 29, 2:35 pm, Matt wrote:
I recently moved into a new house. Several of the exterior vinyl
windows have these strange fingerprints on the outside of the upper
pane just above the meeting rails. I've tried cleaning them with a
razor blade, soap and water, Windex, Simple Green (full strength),
Goo- Gone, Goof-off and Turpentine. With tons of elbow grease,
I'm able to get the fingerprints off - with no one product
obviously dissolving whatever the fingerprints are made from. Still,
when I go to clean the window afterward, just spraying a
soapy solution to squeegee, you can clearly see where the
fingerprints are - even though the window is mostly clear. I have
19 windows to go and dread the thought of having to spend 15-20
minutes on each getting these prints off and even then - not
really getting them all the way off. Any ideas what they could be
and what would dissolve them without damaging the glass or
windows?
Try these things, in this order, or based on what you already have
in the house.

WD-40
Lighter fluid (Rossignol or Zippo, not charcoal)
Acetone

Caution about the Acetone. Do not get it on the vinyl as it will
cause damage.

Sounds like somebody in the factory had bare dirty hands when they
assembled the sashes or the windows. Residue from the glue that holds
the glass panel in the frame, I suspect. Warm solvent, warm vinyl,
glass surface that it is cleaner than it will ever be again, viola,
permanent fingerprints on the glass. A more permanent version of the
wiping pattern you see on the inside of your windshield when you fire
up the defroster, even though the glass looks perfectly clear in
bright sunlight. Glass ain't solid, it is a supercooled liquid. Not
that hard for stuff to bond with it.

this is not correct. it is not a supercooled liquid. it is an amorphous
solid.

http://www.obscure.org/physics-faq/G...ass/glass.html

Having said all that- let go of the OCD- nobody else notices or cares.
First good rainstorm, the light layer of haze on the outside of the
glass will hide all until you scrub again.

regards,
charlie
http://www.glassartists.org/ChaniArts