If you have stubborn stuff on the surface of a mirror or glass your finger tip is still softer than any cotton wool or fabric you'll ever find. You'd be buggered to scratch any coating with soft skin. Added benefit is you can feel any particle on it. When you're done 'shampooing' just rince and blow dry then of course when done keep you finger tips away from it.
If you have stubborn stuff on the surface of a mirror or glass your finger tip is still softer than any cotton wool or fabric you'll ever find. You'd be buggered to scratch any coating with soft skin. Added benefit is you can feel any particle on it. When you're done 'shampooing' just rince and blow dry then of course when done keep you finger tips away from it.
I recall reading somewhere (may have been the ATMlist) back looong ago when I ground my first mirror, that a clean palm is best when cleaning a mirror?
I know when I was polishing, my fingers left prints or streaks but the plump bit of my palm(muscles for thumb) never did.
Supposedly the palm is soft like fingers, but does not have the greasy/acidic sweat that our fingers do.
This could be complete hogwash due to bad memory tho..... but I must have read it somewhere 'coz I would have done it a hundred times while polishing and it never once scratched or streaked.
I usually immerse the whole glass in a sink with tap water (warmish) and some of the Kodak photo flow solution. When the mirror is underwater if you lightly touch the surface with your index you can feel any hot spot. Just rub gently until lose. It's super quick to find where the grime is. Then I rinse it in cold water under the tap. The stream of water will run straight off the mirror and grab any isolated drops. Any drop that stays will usually stick to something that shouldn't be on the mirror but with a bit of practice you can 'stick' them to the stream. You can actually rinse your whole mirror dry without even touching it because the water will run off it. What ever drops are left just blow them out of the way and that's it. I know there is an argument about distilled water but in my experience running clean water doesn't leave any marks. In my area anyway. Could be a problem if you have hard water.
I had a strange event, before I got a dew heater or shield, in which condensation (dew) formed on both the inside and outside of my SCT corrector lens, leaving quite palpable marks all over the inside of the lens (the outside stuff evaporated cleanly). Very odd.
I cleaned the lens much as Marc cleaned his mirror in the post above. Very gently in a bowl of clean tap water. Seemed to do the trick and the issue has not recurred.
I can only presume there was some sort of residue from the factory ...
Just on this topic, I was watching a DVD produced by Dave Kriege of Obsession Telescopes last night. He had a section in which he demonstrated cleaning a primary.
His recommendation was that a primary should be cleaned once a year. The secondary should be cleaned more often given its greater exposure to dust particles etc.
Specifying a recommended time between washes is non-sense. If the mirror looks foggy or unclean - wash it . Refractor users would not let their lenses get into the state reflector mirror owners tend to let their mirrors get into. Why ?
Better still let your mirror become a cess pit - take astrophotos then post a picture of your mirror so people may marvel at how good your pictures were with a dirty mirror http://www.iceinspace.com.au/forum/a...e.php?a=145670
Strange options in the poll, I think its its best to clean the primary when its dirty, whenever that may be. Could be years, or days depending on the environment and aggressiveness of the material that lands on the mirror. Mark
What do people think about using acetone as the final stage of cleaning. I have never used it but would be interested to hear other views.
It would have to be analar grade otherwise dissolved impurities might be left behind , also acetone is something I'd be wary of in enclosed areas for both health and fire hazard reasons. Can't really see an advantage as acetone is not miscible with water so would only be of use on a dry mirror.
Philip
I agree with Mark, my preference is not listed as an option. I have
never cleaned a mirror in nearly 50 yrs of owning reflectors, but not because I might harm it, just because I have never observed any
deterioration in the image.
raymo
i use acetone -dont have a problem with it -if the coating is applied properly it shouldn't just wash off.
a mirror with overcoating can be washed fairly frequently -the overcoating should last for ages -
the mirrors without overcoating need more care taken, but i still wash at least once a year in the sink before i do the dishes, rinse with water
I think the more important item should be -how you you prevent your mirror getting dirty -seal the tube as much as possible -& look after the OTA
Please be careful with ventilation if using acetone, as Philip warns. In 1963, a senior biochemist at Adelaide University was killed when acetone vapour in his lab exploded.
Can't really see an advantage as acetone is not miscible with water so would only be of use on a dry mirror.
Acetone is perfectly miscible with water in any ratio, much like alcohols. I use about 25% water and 75% acetone as my cleaning fluid, this makes cleaning easier as the solution doesn't instantly evaporate (like acetone does).
Due to my environment, and the haze that builds up on my mirror, I clean it every 3-4 months. Going longer results in a noticeable loss of brightness and contrast. When I clean the mirror, and make a swipe across the wet mirror, then rinse it off, there is always a shiny streak in an otherwise dull surface.
For my scope, that's one cleaning about every 40-50 hours of use. I couldn't answer the poll because my answer wasn't there.
