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please tell me who sells distilled water...


estwing

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You can probably get deionised water in any garage. As you know the object is to rinse off the mirror without leaving a residue. Most of the contaminants in water are dissolved mineral ions and deionisation by passing the water through a resin filter removes them very effectively.

Works for me anyway.

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It's funny, but I spent much of my career working with lasers using aluminium coated mirrors very similar to the mirrors in the telescopes we own. The way I was trained to clean mirrors was to use ultra-pure organic solvents, usually spectroscopic grade methanol, acetone or isopropanol, and expensive lint-free lens cleaning tissue. At first I was a bit horrified to see that the amateur astronomer's standard mirror cleaning technique was at the kitchen sink with tap water, detergent and a rinse in distilled water. But it seems to work fine.

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Hi


Please note that there is a significant difference between distilled and deionized water - some dependent on where your water is taken from and how treated.


Distilled water is water that has been boiled then condensed (steam allowed to cool) to collect the pure water. When the water is boiled the minerals and other nasties are left behind while the pure water is collected in the condensing process. This is what you should use for mirror cleaning.


Deionized water is water that has been filtered or treated to remove the chemical ions. There may be other materials still in the water after this process, potentially reacting with your surface. This is the type of "water" you'll usually get from DIY car shops.


Some may argue that they've used both types and found no difference.... hell, it's your mirror coating!!


Regards, Les 
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will try the RO water,never heard of it!

RO water (reverse osmosis) is more or less the purest water u can get, I use it to top up my salt water aquarium (drops the salinity of my tank water otherwise the salt content gets too high) costs around £2 for 5 gallons.

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It's funny, but I spent much of my career working with lasers using aluminium coated mirrors very similar to the mirrors in the telescopes we own. The way I was trained to clean mirrors was to use ultra-pure organic solvents, usually spectroscopic grade methanol, acetone or isopropanol, and expensive lint-free lens cleaning tissue. At first I was a bit horrified to see that the amateur astronomer's standard mirror cleaning technique was at the kitchen sink with tap water, detergent and a rinse in distilled water. But it seems to work fine.

I think you may (genuinely) HAVE something there. :p

Instinctively I am (still) wary of water. We used to try to purify organic solvents to a very high degree... By letting them "stew" over *NaK*. Not to be tried at home - NaK is an alloy of Sodium and Potassium, and interestingly a liquid at room temperature! Comes in sealed, evacuated glass vials. I believe it is used as a heat-transfer fluid in nuclear reactors. Whatever, it most certainly didn't like water. :D

Re. purification of water via distillation, I wonder...

http://en.wikipedia.org/wiki/Steam_distillation

A common enough technique in the perfume industry?

Who knows? At least your mirror would SMELL nice!  ;)

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The atmosphere contains lots of dust and pollen (which is how your optics got mucky in the first place), and any water is cleaner than what you're cleaning off, therefore it will remove the dirt from the mirror. If anything is going to damage your optics it's the dirt that's already on it - not anything in the water you clean it with. We know this because you don't rub the mirror, which would grind the dirt into it - you wash & rinse it, then dab with no sideways force. Any damage done during cleaning is due to the cleaning technique, not the solvents used. If you dab the surface dry, there won't be any water left on it to evaporate, so there won't be anything to leave a residue on the optical surface irrespective of whether it was chemically pure or not.

Also, as soon as you've cleaned your optics - with whatever sort of water you use, once you stop cleaning, the optics will start to dirty-up as particulates from the atmosphere start dropping on it again. So unless you have a clean room to observe in, as soon as you take it back outside to use again it won't make the slightest difference whether you cleaned it with distilled, R/O, deionised or tap water. The gunge from the atmosphere will have negated any effects from using "pure" water.

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Hi I use http://www.thedistilledwatercompany.com/ always good service I buy in big tubes every couple of years and store in dark cool place. It takes about 500ml to do a 10" mirror so lasts a while (I also clean the screen on the lcd tv once a month with a damp optics cloth (unplugged and be be careful).

if you dry your mirror with a cold blow hair dryer straight away no marks or streaks. (this cannot be said when using hard tap water, I've tried)

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Water ??? I'm still using I.P.A. to rinse my mirrors, works a treat and evaporates in seconds....available from Maplins and other good electrical suppliers. ( That's isopropyl alcohol for anyone who was wondering ).

Ian

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