Yes, bad idea. Besides contact abrasion, moisture gets trapped beneath the film. I've had excellent results with just making sure the tube assembly is capped on both ends, and the focuser. Then, and here's an important detail, store the tube horizontally, so the mirror surface is vertical. Dust is less prone to settling on a vertical surface. Some people prefer a "contact" mirror cover. In that case, use a breathable, soft material such as felt. It will actually only contact the mirror on the edges unless the f-ratio is very slow, but there is still the probable risk of scratches due to abrasion. I'm surely no expert, but 4+ decades of experience has taught me many lessons. It's an unfortunate fact of life that the people in the shipping department of some optical companies are not highly-paid expert technicians! On Mon, May 5, 2008 at 1:38 PM, Kim <kimharch@cut.net> wrote:
Years ago my 10" Parks mirror came packaged just as you described, with plastic wrap directly adhered to the aluminum surface. So, thinking that Parks wouldn't do anything to their mirror that would cause problems, I also stored it that way. Bad idea. My mirror has permanent marks on it, whether from out-gassing or some other process I couldn't say. The marks look a bit like streaks left from Windex. As near as I can tell the performance has never been compromised, but I am sorry that I marred the surface. BTW, the Parks mirror has been a fabulous investment - well-figured, very sharp images (even at high power) and a joy to use.