Don W
demi-god
Reged: 05/19/03
Posts: 19226
Loc: Wisconsin, USA
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Just leave it alone. You should not have to clean your mirror more than once a year or so. The dust doesn't matter. If it really, really bugs you, then get a camel hair brush to gently flick of the big stuff or a 'puffer' type lense cleaner. I would NOT use dry cotton wool. That just drags the dust over the surface which will do more harm than good.
The first rule of mirror cleaning is "DO NO HARM".
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DON'T PANIC!-Hitchhiker's Guide to the Galaxy
Don Wyman
Obsession 18" f/4.5 #1166
W/Argo Navis DSC and Torus Primary
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Anonymous
Unregistered
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Hello everyone,
I am new to this forum and I found this subject on cleaning mirrors interesting. I clean my mirror with tap water and dishwashing liquid, just wondering if the mirror would be harmed by the dishwashing liquid?
Eddie.
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Jon Isaacs
Postmaster
Reged: 06/16/04
Posts: 32442
Loc: San Diego, California
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The first rule of mirror cleaning is "DO NO HARM".
I add the corollary:
The best way to "DO NO HARM" is to avoid temptation and leave it alone....
I have cleaned my mirrors when they seemed dirty. I have noticed any difference in their performance after I cleaned them....
jon
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MikeS
Pooh-Bah
Reged: 04/06/04
Posts: 1089
Loc: Quakertown Pennsylvania
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Companies really need to have warnings printed regarding mirror cleaning. Way too many people think that these mirrors are like the ones hanging on their walls, and clean them the same way.
Maybe a warning like the labels on cigarette boxes! 
Mike
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Mike Snisky
8" F5 Newtonian/Moonlite CR2
Orion Sirius EQ-G Mount
Astro-Tech AT6RC Ritchey-Chrétien astrograph
Orion 100mm F6
Orion 100mm ED on LXD55 Mount
Denkmeier Standards
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ozzmosis
sage
Reged: 01/20/05
Posts: 377
Loc: MONTREAL
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i just bought mine and i took it apart and cleaned the mirror it s not that much of a job ,, u just have to be very carefull to what u do thats all!...
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Celestron C9.25 moonlte CS, Skywatcher200mm Moonlite CR, Skywatcher mak102mm, Cg5 goto, Orion short 80mm, Canon rebel xs, Philips spc900nc, dbk21au618, Televue 3x. Televue powermate 2.5x, Celestron cel 12.5mm, cel 5mm, 25mm
http://www.flickr.com/photos/74059838@N00/show/
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ozzmosis
sage
Reged: 01/20/05
Posts: 377
Loc: MONTREAL
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ya when i washed mine too i did rinse it with distillated water too it s soft water and wont scratch it ot deposit stuff on it allso i find that using an air can , can be helpfull too gets rid of the few drops left on the mirror worked for me!.,,.
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Celestron C9.25 moonlte CS, Skywatcher200mm Moonlite CR, Skywatcher mak102mm, Cg5 goto, Orion short 80mm, Canon rebel xs, Philips spc900nc, dbk21au618, Televue 3x. Televue powermate 2.5x, Celestron cel 12.5mm, cel 5mm, 25mm
http://www.flickr.com/photos/74059838@N00/show/
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PolBed
member
Reged: 08/19/04
Posts: 22
Loc: Quebec Canada
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How do I know I need to clean it ? What would be the optical signs of a "too dirty mirror?
My 5 inch mirror is a bit less than a year old. On cold nights (-10F), it probably gets a lot of condensation coming back in (yes I do cover before getting in). I can see quite a few of what looks like dried-up water droplets on it.
Two nights ago, trying to split some double stars, I had the impression of seeing "speckles" using the barlow and 10 mm. Also I had the impression that stars had more/larger airy disks than in the past (not sure here).
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DanJ
Pooh-Bah
Reged: 12/01/04
Posts: 1111
Loc: Knoxville, TN
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I don't quite see the "problems" associated with cleaning mirrors/optics. I have a chemical/environmental engineering background and do not foresee any problems associated with a non-abrasive method of cleaning optics for a scope. Granted, you must not apply, or apply very little friction to the glass. Any cleaner, i.e., detergents like metasilicate, carbonate or chlorine will not have any impact on the optics, providing you use minimal friction, if any.
These chemicals lower the surface tension of water and will sheath off any contaminate on a mirror. Therefore, after a good soaking, the only thing you should need to do is give it a good rinse and then rinse it off with Isopropanol (rubbing alcohol, but at 90+ %). Thereby, eliminating any need to perform a wipe down to dry it off, as the Isopropanol will evaporate any residue.
Just my two cents worth...
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Dan J.
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XT8i
ETX 90
PST
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"A government big enough to give you everything you want, is strong enough to take everything you have."
Gerald Ford
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donnie3
Carpal Tunnel
Reged: 12/15/04
Posts: 2240
Loc: bartlesville oklahoma
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if you do clean your mirror, dont do what i did and tighten the clamps down on the mirror when i put it back in the cell. it will cause a distorted image. just screw the clamps down until thay just touch the mirror. i collimated my scope 4 or 5 times until i got on a forum and ask for help, took the cell out of the scope and loosen the clamps and reinstalled it in the scope, took it out that night, let it cool down and what a difference, i got a fantastic image.
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Chriske
Kijkerbouw Urania
Reged: 08/15/04
Posts: 2317
Loc: Boechout, Belgium
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The main reason why some mirrors seem to degrade faster than another is :
- because some people close theire telescopes to soon after an evening of observing with heavy dew.
- The second reason is where you store your scope when not in use. If stored in a garage with a high humidity the scope will have to be recoated very soon.
- And the third reason is, do you have a coating or not.
- If the telescope is well treated (as mentioned above), aluminum will last for about 5 to 10 years. With an extra coating it'll stay for about 10 to 20 years.
- On a see climate it'll last less longer.
- Do not touch the optical surface with your fingers. If you did, that's he point where the degrading will start if you have sweaty hands.
I only put a layer of alu on my own mirrors no coating at all. It takes about 2 to 4 days to remove the layers if the mirror hase a extra coating on it. If removing is not done in the proper way your mirror hase to be repolished. That is, you have to use the right product to remove the old alu/coating layer. If to long treated with sulphuric acid (for example) your optical surface is completely destroyed. Have done it once by accident on a 250 mm primairy mirror from a Kutter telescope. 
Nowadays whe only use 'Green River'. It's a product used to remove the 200" telescope's old layers at MP. If i'm not mistaken you will find the exact ingredients for this product on the MP site.
We've done some testing after treatment with several products, products of whitch chemists told use it was absolutely 100 % safe to use on glass(did they know it was optical glass). Do i have to say more..
Good advice : if your mirror hase to be recoated and you have the possibility and the place to remove the coating yourself, just do it.
Or ask the people who are going to treat your mirror what product they'r using to remove the old stuff.
Edited by Chriske (02/06/05 03:23 PM)
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PolBed
member
Reged: 08/19/04
Posts: 22
Loc: Quebec Canada
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interesting advices but optically how would I know the trouble is the dirty mirror or what are the effects. According to a friend here I would just loose some light nothing more. Resolution for splitting doubles should not be affected!
From those who cleaned their mirror, what kind of improvement did you notice afterward?
Thanks again for your inputs,
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Jon Isaacs
Postmaster
Reged: 06/16/04
Posts: 32442
Loc: San Diego, California
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>>From those who cleaned their mirror, what kind of improvement did you notice afterward?
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I clean my mirrors every so often, mostly when I am removing them for some other reason and I just decide to do it. As far as before and after, the only thing I have ever noticed is that the mirror looked cleaner, looking at the night sky, no effect....
jon
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Andy S.
super member
Reged: 02/22/05
Posts: 191
Loc: Europe
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Now this might be a obvious NO NO to every one here on the forum for a to me not immediately appearant reason, but to me it seems that since it is such a big deal not to touch your mirror surfaces with your fingers, people should wear Latex Gloves when doing work on Mirrors and Collimation. But why has no one suggested using these in their Cleaning instructions or did I just successfully overlook that? Or is there any reaction of the Mirror's surfaces to the latex??
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So Long: Andy 
Orion 8" f4.9 SkyView Pro EQ
Pentax 10x50
Sony DSC-P93
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Chriske
Kijkerbouw Urania
Reged: 08/15/04
Posts: 2317
Loc: Boechout, Belgium
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Indeed Andy, while working on your mirror it would be wise to wear some gloves. But i admid never using them because there very uncomfortable...  But even while wearing gloves you should avoid touching the surfaces.
But while cleaning the optics it is not realy necessary or even not adviseble.
1- Because your hands are constantly in the solution(s) your working with, your hands are clean.
2- It is even dangerous to wear gloves, depending on the kind of solution you'r working with and also what kind of gloves you are using the mirror gets very slippery..!
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Chris
Edited by Chriske (03/02/05 05:56 PM)
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square_peg
Postmaster
Reged: 03/26/04
Posts: 36712
Loc: Maple Valley, WA
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There's no need to touch the front surface of the mirror during cleaning. Just let it soak for an hour or so in your cleaning solution then rinse thoroughly with tap water, then distilled water. If that doesn't do it and you need to physically wipe the mirror, do it under the cleaning solution by very gently dragging a sterile cotton ball over the mirror. One short swipe with each cotton ball, then throw it away and get another one. I found it took about 20 cotton balls to clean an 8" mirror. This was on a donated club scope that had been stored in a garage and was covered with exhaust fumes. It cleaned up very nicely.
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Tom (Pegster)
DSH-8 (GSO Dob)
15x70 Oberwerks
ED80/SVP
WO 66P
Sears Discoverer EQ 60/900
8x42 Regals
History is Philosophy teaching by examples.
Thucydides
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Anonymous
Unregistered
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 I used a 50-50 mix of tap water and clorien ONCE  8 years old in my grandfathers garage on his telescope 
Ah the memories..............
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gezak22
professor emeritus
Reged: 08/15/04
Posts: 576
Loc: Goleta, CA, USA
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Is it okay to use nothing but distilled water for cleaning the main mirror?
I have read numerous posts where people suggested to rinse the mirror with tap water first and then with distilled water. Suppose I rinsed it with distilled water only, would that harm the mirror in any way?
Do you actually have to let the mirror soak in a cleaning solution? I would just rinse it with distilled water and let it dry. That sounds hard enough.
Great thread.
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Geza.
http://geza.zenfolio.com/
Plan your shoot and shoot your plan.
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froggy38383
member
Reged: 12/02/04
Posts: 45
Loc: Brandon Manitoba Canada
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I bought a used 8" not long ago. Yesterday I took out the mirror. It had a healthy dust film on it. I did a careful cleaning and I don't regret it. It is not difficult. As long as a person is careful there is nothing to worry about.
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Oberwerk 20 x 90 binoculars
8" starhopper dobsonian
Fisher-Dietz 7 x 35 binoculars
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Anonymous
Unregistered
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Well it is time...
I've only had my scope maybe 2 months, but I apparently don't know alot about dew.
It seems I have brought my scope in too quickly when dewed up and sealed it up.
I have collected quite a bit of particulate on the thing.
Went out and bought some 91% rubbing alchahol, some distilled water, a camel hair brush, some sterile gauze pads, and a plastic sink insert.
It's time to give it a try.
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Anonymous
Unregistered
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Hey guys, just over a year now since my introduction to dobs... if I shine light on the mirror sideways, the dust is quite evident. I don't believe it affects deep sky at all, but I suspect it is a significant contributor to light scatter around bright planets. Building a new scope for the mirror now ("The Challenge" thread over in ATM). I plan to clean the mirror before first light, so will be looking for all the advice I can get.
Doug
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