Mirror Coatings

I have seen some adds for used mirrors that say "could use recoating". Why would a mirror need recoating?

Darryl

Hi Darryl,One of us is spelling our name wrong.The reason a mirror may need to be re-coated is that time and certain atmospheric conditions such as smog or even chemicals that get in the dew can and does eat the aluminum off the surface.You should never touch a mirror also,this will also take the coatings off from just the acids in your skin.You should always make your tube is as airtight as possible when not in use.If you store it in your house just steam from cooking will carry grease and will deposit it on your mirror.Try to not clean it if it just gets dust on it.Over cleaning also rubs off the coating.Remember the coating is on the top and not underneath like a looking glass and is very fragile.I use the old type bathing caps on my scopes as well as the dust cap that comes with it,and since I keep it in an envirionmenally kept outside building I also keep them covered with plasic garbage liners.They accumalate a lot of dust but when I get one of my scopes out it's like brand new without a speck of dust even on the mount.Clear skies,Darrell