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View Full Version here: : Should a 1mm layer of dust affect a mirror's performance??


glenluceskies
08-02-2010, 07:04 AM
I am joking in the title, of course. :lol: I went to have a look at our 8" Dob "grab-n-go" scope stacked in the corner of the shed and realised I had left the mirror cover off it. As a result it had a nice 1mm layer of dust, sawdust and fluff (and goodness knows what else). Put it this way, you could not see your own reflection. Ooops.

Anyway I followed the excellent article in the Projects section here (http://www.iceinspace.com.au/index.php?id=63,345,0,0,1,0). Filled the sink up with water and washing up detergent. Lowered the mirror in to the water and used cotton wool balls to gently wipe over the surface of the mirror. Then rinsed with tap water for a minute, then rinsed with distilled water for another minute. Left it to dry and ended up with an "as good as new" mirror!

The only imperfection is a small "scuff" mark where I accidently brushed the back end of a screwdriver handle on the surface. It measures 2mm x 0.5mm. Hardly worth worrying about, in my opinion. For a 13+ year old mirror, I see no blemishes, or any fomr of tarnishing to the surface or edges.

Then I did the same for the secondary mirror. I didn't even bother removing it from the holder, just unscrewed it from the spider and cleaned it in the same manner. There appears to be a tiny amount of tarnishing" on one edge, but I doubt this will affect its performance.

Starkler
08-02-2010, 07:46 AM
You probably did this but didnt mention it here. FOr the viewers at home I recommend flushing away the loose crud before putting the mirror in its soapy bath. :whistle:
You want to minimise contamination of the water before touching the mirror surface.

glenluceskies
08-02-2010, 07:51 AM
Yes Geoff, I forgot to mention I gave it a light rinse first! Thanks