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Is my mirror Ruined?


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Ok this is a new problem I encountered last night while looking at Jupiter, while waiting for Saturn. I'm not sure you guys will believe me but here goes...while I was look at Jupiter last night with my scope pointed some where between 60 -70 degrees a Flying Fox (Fruit Bat) flew over me and pee'd down my scope. Now don't laugh, Please. So I put some tissue on a stick and tried to clean it. When I got home from Work today I thought I had better just look and see if it was ok. On that inspection I could see a lot of tiny little black dots and 1 big black dot. The tiny Dots go all across my mirror and the big black dot is just below centre and to the left a little. Can I clean it more or do I need a new scope? I believe the mirrors are very easy to ruin

Eagerly waiting any help.

Squidie  

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I would give it a wash ASAP as per this method:

As long as nothing abrasive has contacted the mirror and that any residual Fruitbat wee is carefully washed off it should be OK. I'd not leave it for long though in case the acid in the wee affects the coating of the mirror.

The black dots in themselves won't affect the views.

 

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Yep, give it a wash and depending on how big it is (cant be done with a big mirror, but works great for secondaries) - give it a good shake to get residual droplets off, or quickly blow them off with a rocket blower... that will reduce the chances of any water marks that may arise from using non-pure water when you rinse it.

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That was so unlucky, but those fruit bats are huge, I have seen them a few times while visiting Australia, if you can get

some distilled water, then use that for the final rinse off, it stops getting water marks, good luck with the clean, your mirror 

should be OK.

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5 hours ago, Uranium235 said:

Yep, give it a wash and depending on how big it is (cant be done with a big mirror, but works great for secondaries) - give it a good shake to get residual droplets off, or quickly blow them off with a rocket blower... that will reduce the chances of any water marks that may arise from using non-pure water when you rinse it.

Can DI (de-ionised) water be used for the final rinse?  In work we use this if we need to clean PCBs without leaving the residues caused by tap water.

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2 hours ago, Starwiz said:

Can DI (de-ionised) water be used for the final rinse?  In work we use this if we need to clean PCBs without leaving the residues caused by tap water.

Yep, thats what I use - but it still needs to be gotten off as much as possible before drying because it does leave some marks if left to evaporate. You will find distilled water very hard to obtain off the shelf, it can be gotten online or via a pharmacist (who has to order it in).

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There is a chance that the initial tissue on a stick left a scratch or two. Probably not the best approach but then I don't know much about the chemistry of bats bodily fluids! If it's high in ammonia or otherwise corrosive it's probably best to get it off as soon as possible.

The good news is that small dull or non-reflective patches don't affect the performance of the mirror so much. Scratches do, if bad enough, because they can scatter light causing loss of contrast.

Good luck with the washing. Any chance of some before and after pictures?

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2 hours ago, Uranium235 said:

Yep, thats what I use - but it still needs to be gotten off as much as possible before drying because it does leave some marks if left to evaporate. You will find distilled water very hard to obtain off the shelf, it can be gotten online or via a pharmacist (who has to order it in).

Bear in mind there may be a difference between distilled and de-ionised.

http://www.distilleddeionizedwater.com/deionized-water-vs-distilled-water/

If DI water isn't available, I think distilled would definitely be better than tap water and, as it's used for topping up car batteries it can be obtained from places like Halfords, etc.

Drying as much as possible also has to be good.  I have never done this, but if I had to, I would probably stand the mirror on edge (supported) and use a hair-dryer to blow the moisture downward.  Please correct me if this is known to be wrong in any way.

John

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I probably wouldnt use a hairdryer (it wouldnt have enough "puff"), and it might blow more contaminants on to the mirror. Normally, there are only a few droplets left so a blower would be good enough to move them off the mirror.

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24 minutes ago, Uranium235 said:

I probably wouldnt use a hairdryer (it wouldnt have enough "puff"), and it might blow more contaminants on to the mirror. Normally, there are only a few droplets left so a blower would be good enough to move them off the mirror.

Yes, makes sense.

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Awesome news ...thank you to every one...even the people that had a laugh. Unfortunately I see this happening  a lot ...with the bat colony of hundreds if not a couple thousand less than 1 km away form my house. 

I'll get right on it.

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13 hours ago, Starwiz said:

Bear in mind there may be a difference between distilled and de-ionised.

http://www.distilleddeionizedwater.com/deionized-water-vs-distilled-water/

If DI water isn't available, I think distilled would definitely be better than tap water and, as it's used for topping up car batteries it can be obtained from places like Halfords, etc.

Drying as much as possible also has to be good.  I have never done this, but if I had to, I would probably stand the mirror on edge (supported) and use a hair-dryer to blow the moisture downward.  Please correct me if this is known to be wrong in any way.

John

I think also that there is a difference between de-ionised and household 'softened' water. IIRC softened water is obtained by passing the water through an ion exchange resin, which exchanges the calcium ions with sodium ions (which is why you replenish the resin with brine). So it will still contain salts which could leave a deposit as it dries. Better to go with de-ionised or distilled I should have thought.

Ian

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On 31/03/2016 at 11:34, Squidie said:

I see this happening  a lot ...

There's a very thin plastic film used for adding an insulating barrier to single glazed windows and when heated with a hairdryer it will contract and become extremely transparent...if I had your problem I think I would test it as a barrier against the bat pee. The film is very inexpensive and you would either have to make a round collar that fits over the end of the scope or use double sided tape to stick the film too. Not sure what impact it would have on the optics, you may get reflections?

I use a stirrup pump to blow any water droplets left from the final rinsing, it's very powerful and no risk of contaminants but requires a second person to operate the pump.

Good luck.

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