When I received the 30" Obsession a few months ago, the mirror was a little dusty. Ordinarily, I let dust go a while, as it doesn't have a discernable impact on viewing. After I traveled down some horribly dusty roads on the way to Iowa Star Party, I was shocked to discover that a pretty heavy layer of dust had managed to get inside the trailer, and some even on to the mirror. So, by this time, the mirror was looking pretty filthy.
Tonight, I decided to take on the challenge of cleaning this beast. This mirror weighs over 200 lbs, so removing it from the mirror box, is really impractical. If you've seen Dave Kriege's old Obsession videos, you've seen his demonstration on cleaning a 25" mirror, INSIDE the mirror box. Of course, the scope he was cleaning, was bare bones, had no electronics. My 'Anzio Annie' has all sorts of circuitry running through the rocker supporting the mirror box, which would quickly be destroyed, should it be exposed to water.
My solution, was to simply run a tarp below the mirror, with the mirror box tilted such that the mirror was perpendicular to the ground. Any water I poured over the mirror, would fall onto the tarp and roll out the back of the mirror box, on to the ground, and well away from the electronics.
So, the cleaning process just involves, pouring the (hardly noticeably) soapy distilled water across the surface of the mirror. Further wetting down with the atomizer, I took a bunch of cotton balls in my hand, and carefully slide them across the surface to pick up loose debris. No force needed to be applied, accept carefully where a piece of grit didn't come off easily.
After wiping down with the 'soapy' water, I poured another jug of clean distilled water across the mirror surface to rinse. Distilled water is such, most of it just sheets down and off the mirror. For the few drops that remain, I use a virgin micro fiber cloth, using only the weight of the cloth itself to pick them up.
The result, was a beautifully shiny Russian primary mirror. I generally don't clean a mirror more than once per year. It's just not worth it, the less one touches their polished mirror, the better.