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PLEASE HELP- did I ruin my mirror?


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Hi, I followed cleaning guides for my mirror (tap water followed by distilled), however I don't have distilled water so I used 99.9% isopropyl. It left this yellow-green tinge. Am I screwed? Please help ūüėß

2020-06-21 14.47.10.jpg

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I tried a bit of paper towel, just barely touching the paper against the mirror, like holding one end and letting the weight of the corner drag across this residue and it seemed to come away. Got some water coming today so. Question, is deionised water the same as distilled? If not, will it still work?

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I usually put mine in warm water with a good squirt of Fairy Liquid with gentle agitation for a few minutes then rinse under a running cold tap (never got round to buying distilled water but if you already have it or want it...). Then leave it inclined to allow it to drain and dry. At least that is the treatment my 6.25 in Fullerscope primary mirror has been cleaned with over the years. My 250PDS is 7 years old but not near needing a clean yet. I don't even dust it off. I doubt it's as robust as Ye Olde Fullerscope!

Anyway, if that process doesn't clean your mirror it might well be damaged by the alcohol. Much lower strength alcohol turns me green too :)

Are the two tarnish like marks at 8 o'clock and 12 o'clock new or were they there already?

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I cleaned my 11" SCT using the cleaning instructions from this video, but instead of cotton wool I used Kleenex wipes (as advised by Baader Planetarium) using the same method as shown in the video (please note that the Kleenex should be colourless and odourless and that a lot should be wasted). As fluid I used demineralised water, combined with a simple household washing-up liquid. The last few remaining stains I took off using a Baader cleaning set (you can check for stains by exhaling over the mirror, the moisture from you breath should produce an even layer of water vapour on the surface).

Until you have demineralised water I would follow @Robindonne's advice and leave the mirror under water (although I am not sure if that affects the coating, perhaps someone else here knows).

Best of luck, hope it will turn out crisp an clean again!

Nicolàs

On water types: https://www.westlab.com/blog/2017/11/29/the-difference-between-distilled-and-demineralised-water

Edited by inFINNity Deck
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20 minutes ago, greg110902 said:

 It's strange, some guides say that isopropyl is okay.

I'm no expert but I guess there are mirror coatings and there are mirror coatings. Not all will be known to the writers of such advice!

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Update:

So in the end, I threw caution to the wind. I figured there's a chance this mirror is useless now, and I found I can buy a new one for ~£30. So, I rinsed it under deionised water, and cleaned away marks with a dishcloth. It looks okay, everything looks sharp and I popped it back in the tube and checked it out with some terrestrial viewing, everything looked up to standard. Looks like it could be a clear night here tonight-we shall see (or maybe I won't)

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3 minutes ago, greg110902 said:

Update:

So in the end, I threw caution to the wind. I figured there's a chance this mirror is useless now, and I found I can buy a new one for ~£30. So, I rinsed it under deionised water, and cleaned away marks with a dishcloth. It looks okay, everything looks sharp and I popped it back in the tube and checked it out with some terrestrial viewing, everything looked up to standard. Looks like it could be a clear night here tonight-we shall see (or maybe I won't)

That's great news and a lesson learned too!

If the mirror is now tarnish free then it'll be fine. Minor scratches in the coatings and pinholes in the aluminising make little difference. 

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1 minute ago, Paul M said:

That's great news and a lesson learned too!

If the mirror is now tarnish free then it'll be fine. Minor scratches in the coatings and pinholes in the aluminising make little difference. 

Yeah, lesson learned. I make £5 an hour so you can imagine how worried I was to lose a £180 scope! Haha.

Anyway, thank you to everyone that helped. Really appreciate it.

 

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Are you sure it was isopropanol or IPA or (using the old name) isoporpyl alcohol that you used?
Was it known to be pure stuff and new?

I use IPA in parts of optics cleaning and have never encountered anything like this.

Anyway, a good outcome at the end of a stressful day.

David.

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2 minutes ago, Carbon Brush said:

Are you sure it was isopropanol or IPA or (using the old name) isoporpyl alcohol that you used?
Was it known to be pure stuff and new?

I use IPA in parts of optics cleaning and have never encountered anything like this.

Anyway, a good outcome at the end of a stressful day.

David.

I'm pretty sure it's good, it's about 6 months old, I'm at a loss as to why it caused this, I've used it around pretty sensitive electronics where it really has to be high purity. Maybe the manufacturer just used a coating which happens to react with isopropyl. Oh well, all's well that ends well.

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4 hours ago, greg110902 said:

Update:

So in the end, I threw caution to the wind. I figured there's a chance this mirror is useless now, and I found I can buy a new one for ~£30. So, I rinsed it under deionised water, and cleaned away marks with a dishcloth. It looks okay, everything looks sharp and I popped it back in the tube and checked it out with some terrestrial viewing, everything looked up to standard. Looks like it could be a clear night here tonight-we shall see (or maybe I won't)

I don't think you've ruined the mirror, it just may need re-aluminising, the coating possibly wasn't in very good condition in the first place.

John 

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A lesson to be learnt here I think

LEAVE YOUR MIRROR ALONE 

I have never washed or cleaned my mirror. Its been in the scope for years. And I read an article some years ago about the mirror coatings are so so easily damaged. So unless your mirror is in really terrible condition then personally I would not clean it 

 

 

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As I understand it, mirrors are usually overcoated ie: have a protective coating applied over the reflective coatings.

It has been known for certain brands not to apply overcoats to their mirrors. The mirror works fine but the reflective coatings degrade faster than they normally would had the overcoating been applied.

It is possible that a mirror that is not overcoated could react differently to a coated one when something like isopropyl is applied.

Unfortunately it is not possible to tell an overcoated mirror from a non-overcoated one just by it's appearance.

 

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12 minutes ago, Timebandit said:

 

 

A lesson to be learnt here I think

LEAVE YOUR MIRROR ALONE 

I have never washed or cleaned my mirror. Its been in the scope for years. And I read an article some years ago about the mirror coatings are so so easily damaged. So unless your mirror is in really terrible condition then personally I would not clean it 

 

 

Personally I don't agree with this, obviously it is best to try to avoid the mirror getting dirty in the first place and reduce the need for cleaning to a minimum, but Newtonians or scopes where there isn't a corrector plate or optical window sealing the tube, will eventually need cleaning at some point, unless one is prepared to put up with significantly reduced performance. I agree with John, and think that the problem in this instance may have been a poor quality coating in the first place.

Most coatings you get these days seem to last a lot longer than they used to, I can remember in the 1970's it was normal to have a Newtonian mirror re-aluminised every 3 to 5 years, nowadays they seem to last much longer. I last had my 14in Newtonian re-aluminised in 2013, and opted for the Hilux coating from Orion Optics UK, and it it is still in very good condition after 7 years, much better than would have been the case with traditional aluminising 40 years ago. I usually give my mirror an annual clean, using first soapy water, and then a first surface cleaner such a Baader Wonder fluid, finally rinsing off with distilled water, care is however required at every stage.

John 

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25 minutes ago, johnturley said:

Personally I don't agree with this, obviously it is best to try to avoid the mirror getting dirty in the first place and reduce the need for cleaning to a minimum, but Newtonians or scopes where there isn't a corrector plate or optical window sealing the tube, will eventually need cleaning at some point, unless one is prepared to put up with significantly reduced performance.

I wash mine fairly regularly and I think it does make a difference- maybe my flat is particularly dusty but it quickly gets a dullness from dust deposits. I start with isopropanol then fairy and fast running water then de-ionised water and a hairdryer set on cold to blow the droplets off at the end. Don’t touch it with anything  other than air and liquid.

i very much doubt the op’s green film was the mirror coating- it’s a mineral coating similar to that used on lenses etc -silicon dioxide (quartz) usually I think, and won’t be dissolved by alcohol. They don’t varnish mirrors or at least I’d hope they didn’t! More likely it had built up a film of something in the air where it was stored or my bet the isopropanol was contaminated with something?

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3 minutes ago, markse68 said:

i very much doubt the op’s green film was the mirror coating- it’s a mineral coating similar to that used on lenses etc -silicon dioxide (quartz) usually I think, and won’t be dissolved by alcohol...

I agree - my point was that some mirrors don't have an overcoating (quartz or otherwise) I was wondering if those would be affected by the isopropanol.

 

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3 minutes ago, John said:

I agree - my point was that some mirrors don't have an overcoating (quartz or otherwise) I was wondering if those would be affected by the isopropanol.

 

I’m not a chemist John but I’m pretty sure aluminium is fairly safe in alcohol too. But if it was contaminated with some caustic chemicals then that would be bad!

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7 minutes ago, markse68 said:

I’m not a chemist John but I’m pretty sure aluminium is fairly safe in alcohol too. But if it was contaminated with some caustic chemicals then that would be bad!

I'm not a chemist either but I believe that isopropyl does react with aluminum. Which is why I wondered if this mirror did not have overcoating, or had poor quality overcoating.

 

 

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