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Acetone cleaning of mirror

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#1 John rombi

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Posted 28 June 2018 - 12:07 AM

After cleaning my 12" mirror, I've noticed that there's still some marks that have not come off with water & mild detergent.

 

I've read that acetone is a good solution for removing these marks.

 

What are the protocols when using this chemical: eg gloves, mask for me.

 

How do I apply it to the mirror?

 

Any help would be greatly appreciated. smile.gif smile.gif


Edited by John rombi, 28 June 2018 - 12:07 AM.


#2 SMark

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Posted 28 June 2018 - 12:30 AM

I've cleaned lenses with acetone. Wear nitrile gloves & eye protection, use cotton swabs or cotton balls to apply. Acetone evaporates quickly, so you need to work rather quickly, and you will often need to use more of it than you think you will. It can leave streaks that you will have to come back to remove. Don't use Q-Tips, as they have adhesives and stuff added to the cotton that your mirror will not like. I use McKesson Cotton-Tipped Applicators STERILE.


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#3 sg6

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Posted 28 June 2018 - 02:09 AM

Pesonally I would not ue acetone, reason is that it is a fairly strong solvent and I have lost a couple of items - none astro or glass etc - when I tried it. Have used acetone a few times and for a mirror it would be a last resort. Too many things have gone wrong.

 

I cannot see why it would not work, but there exists the chance that you could clean the mirror and get more off then expected. Any pinholes in the coating will allow acetone through. The coating will I expect be SiO2 so acetone should not directly harm it. SiO2 being basically glass. If you have marks then what are they from. If "dirt" then gently wet them and keep them wet for a while to loosen whatever is there.

 

Are the marks caused by pin holes in the coating and so oxidisation of the aluminium reflection surface? If so acetone will get at the aluminium by the same method.

 

Keep it off your hands, it being a good solvent will take all the oils etc from your fingers. don't sit above the fumes as you will breathe them in and I suppose could pass out - like ether on a cloth idea. Acetone is not uncommon, women use it to remove nail varnish - that is the easy way to buy it in small amounts, ask at the cosmetics section of a supermarket. I used it for rod (fishing) building - to clean surfaces and clean up the assorted mess I would create on the blank.

 

Concerning its strength it will clean off a set 2 part epoxy varnish on a rod. So consider thgat the rod coating is intended for 5 to 10 years outdoor use at the sea in all weathers, and acetone removes that fairly easy. Not tried but I think it will dissolve Areldite epoxy glue.

 

People (and I) have used IPA. Seems a bit less aggressive. It is said it doesn't leave a deposit but I have always had to clean and "polish" anything I have used it on afterwards.

 

I would identify whatever the marks are first.



#4 KGE

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Posted 28 June 2018 - 04:39 AM

The main  issues with acetone are it is volatile and flammable; it is potentially a fire hazard in large amounts and, as noted above, skin contact should be avoided. Respiratory protection is a good idea especially with large amounts. Acetone will not react with SO2 or aluminum.

 

Acetone is also chemically reactive and will undergo self-condensation (diacetone alcohol, mesityl oxide, etc) leading to less volatile residues. I would recommend reagent grade material for cleaning optics. Acetone from hardware stores is questionable. 

 

IPA is less polar than acetone and is not as effective at removing residues but it still works well. Note that most IPA is either 70% or 91%, the remainder being water; as it evaporates you will end up with water on your optics.

 

Kevin



#5 Myk Rian

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Posted 28 June 2018 - 06:19 AM

Even though it is also flammable, many people use 91% iso alcohol.

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#6 Jon Isaacs

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Posted 28 June 2018 - 06:28 AM

After cleaning my 12" mirror, I've noticed that there's still some marks that have not come off with water & mild detergent.

 

 

How did you clean your mirror?  This works:

 

https://youtu.be/9Y8xFnXFVGQ

 

If you're using cotton balls instead of your fingertips , your current results are to be expected. 

 

Jon


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#7 Binojunky

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Posted 28 June 2018 - 10:10 AM

To be honest if the remaining marks are minor I would leave well alone, they won,t make any or only a minor difference, not visible at the eyepiece, Acetone is IMHO nasty stuff, I only used it once and it damaged the coating on an inexpensive refractor, it attacks  plastic and paint, in going after small marks you run the risk of putting a permanent scratch on the mirror,D.


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#8 Mike Lockwood

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Posted 28 June 2018 - 10:43 AM

Alcohol or acetone are great solvents for cleaning mirrors.  They will break up organic molecules that water or soap may not, but then you may need to rinse immediately with water and/or soapy water in order to remove what the acetone broke up before it evaporates.  They will not chemically harm a normal aluminum coating or overcoat.

 

Soap and water may remove things that the solvents may leave behind, so a multi-stage cleaning and repitition of it may be necessary.

 

If I am using any significant amount of acetone, I use it outdoors.  Gloves and goggles are a good idea if you're using a lot of it.  Start with a little on a cotton ball so you can get used to how fast it evaporates.  Alcohol will evaporate more slowly.

 

Obviously I only use acetone with the mirror out of the cell, sitting on something that the acetone won't harm.  And of course stay away from any source of heat or flame or you might have a really bad day.


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#9 MrJones

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Posted 28 June 2018 - 10:50 AM

Meguiar's Perfect Clarity Glass Cleaner is still my favorite glass cleaner. I've cleaned my 12" mirror a few times now with it - so good. Use cotton or new microfiber (I am seeing problems with washed microfiber) and try to swab while avoiding rubbing. Acetone works ok for especially any sticky stuff detergent does not remove, but can leave residue and is not the most user friendly solvent as per above.

 

https://www.basspro....y-glass-cleaner



#10 starcanoe

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Posted 28 June 2018 - 11:28 AM

Just a note.

 

When I clean a mirror...I rinse and soak and rinse and soak for a geologic age...doing my best to get anything remotely abrasive off first.

 

Then, when any "scrubbing" get called into action...I wad up a fair bit of toilet paper....in a roll of sorts...let the bottom half get soaked...then slowly drag that soppy soft mess across any offending area...IMO that greatly reduces the chances of any damage to the mirror coating...

 

my two cents...



#11 SMark

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Posted 28 June 2018 - 11:33 AM

Acetone is very useful for cleaning optics, though I never would use it as my first order treatment. But there are old stains that acetone and elbow grease will remove that nothing else will. Use it when you really need it, and then use it carefully. Acetone will melt plastic and dissolve paint.


Edited by SMark, 28 June 2018 - 11:57 AM.

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#12 JeffreyAK

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Posted 28 June 2018 - 11:59 AM

Acetone will harm paint and plastics, but it won't do any damage to your mirror. It might not help either, but no damage.  The only time I used it on a telescope mirror, it was in hardware-store "100% acetone" variety, and it left a nasty film that kept coming back as a blue haze after letting the mirror sit for a few minutes.  Running water, Dawn dishwashing detergent, and finger tips took care of it, but it was absolutely necessary to follow the acetone with traditional soap-and-water cleaning.  On the other hand I've used research-grade acetone to clean lenses and prisms and it's been fine.  For a telescope mirror, I don't think it matters as long as you follow the acetone (whatever grade) with soap-and-water cleaning.


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#13 Chesterguy1

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Posted 28 June 2018 - 12:10 PM

Acetone will harm paint and plastics, but it won't do any damage to your mirror...

Agreed, we use it with some regularity in our printmaking studio.  It works well for removing unwanted bits on developed photo-positive plates and is fantastic for removing the spray mount we sometimes use to adhere plates to the bed.  It is quite aromatic and hazardous.  We have decent, but not fantastic ventilation (air exchange); however, as was mentioned, it's better to use outside when working with it at home.  When it has gotten onto clear plexiglas it basically etches the surface creating a nasty haze.  As Jeff said it will harm plastics.  I think issues with paint are based on type of paint and how well adhered.  We have gotten acetone onto many, many painted surfaces without issue.  It's possible that over time it will break them down.  It has no appreciable effect on the many glass ink slabs in the studio.

 

That said, we try to use as little as possible.

 

Gogiboy



#14 MitchAlsup

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Posted 28 June 2018 - 03:33 PM

When I clean my big mirrors, I have a board on which I can place them level, pour water and let it dissolve whatever it can, prior to a running rinse. Then I wash the mirror, and then I use another running rinse (water hose) where there are no bubbles in the running water stream.

 

After the water stream (about 3 minutes), I rinse with a cup of acetone to go after what Mr. Lockwood spoke of, and then, slowly, with a gallon of distilled water. Then the mirror is stood up to an 80 degree angle to allow the water to run off. I blot remaining droplets of water. The mirror is removed from the board and returned to the telescope. This method has worked well for me over the last 20 years.


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#15 ctcables

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Posted 30 June 2018 - 06:18 PM

By far the best I have found is Orvus, works very well and I have never had any damage caused to mirror after cleaning.

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#16 John rombi

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Posted 02 July 2018 - 01:45 AM

Thank you everyone, I appreciate all the advice given. smile.gif smile.gif



#17 ctcables

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Posted 05 July 2018 - 05:03 PM

This is a mirror cleaning video I made using Orvus and how great it is. https://www.facebook...0070224408/?t=4




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