In article <495av4$bkq@pulp.ucs.ualberta.ca>, Mail.Address@ualberta.ca says...
>I was wondering if Windex glass cleaner harms optical coatings?

Multicoated lenses are difficult to clean thoroughly. If breath (always breath UP to a lens to minimize spit drops that form nasty mirror spots)
and Kodak lens tissue (or Q-Tips) will not work, Windex applied to a
tissue or swab SPARINGLY, and then to the lens - being careful not to overwet the edges of the lens (resulting in seepage of liquid into the lens), followed by breath and tissue, will clean up most messes. Next
step is alcohol (be careful, again, with quantity!). If that does not work, my ultimate weapon is half-and-half Palmolive dish detergent and
water (it makes a total mess, which is quickly cut when followed by
Windex). Multicoated lenses are a pain to clean, but the up side is that they are much tougher and harder to damage than the older single coatings. BTW, another trick to cleaning lenses is to first thoroughly
wash your hands! (To avoid transfering skin oils to the lens.)
Hope this helps.