Cleaning a primary mirror

[Jaydippy]

Hello all,

I've had my dob for around 10 months now and noticed an appreciable amount of dirt on the primary mirror whilst collimating the scope a couple of days back. I'm not sure if it's dirty enough to justify a clean but it probably will be soon. Unfortunately I have no idea on how to go about this, could someone point me in the right direction? 

Cheers,

Jay

[jabeoo1]

I would say don't clean it unless the views are degraded.  It does not matter if the mirror looks dirty to the eye on the surface its the eyepiece view thats important. 

[jabeoo1]

But if you have to / can't resist:

http://www.dobsonians.co.uk/Mirror%20Care.html

[Tiny Small]

Take it out, put it under the tap. A squish of washing up liquid rubbed in with your fingers whilst under the tap, rinse off and then a second rinse with a bit of distilled water and leave upright to dry. Dead easy and a few minutes work. The distilled water isn't essential but it will massively reduce watermarks afterwards. It also helps to use warm water and leave the mirror in warm water for a few minutes prior to cleaning as this helps evaporation at the end.

[Jaydippy]

Thanks for the prompt response guys.

I can't say that I've noticed any change in the view...but maybe it's like growing taller, too gradual to notice. Trouble is, now that I've seen the dust, anything and everything will be it's fault.   The guide

Sounds easy enough...almost too easy tiny. Shouldn't I treat it the same way as I do eyepieces? I usually give them a clean with an ethanol and water mix, which tends to work well on any dirt/grease. Could this replace the washing up liquid?

[BlueAstra]

This is the method I used. It worked really well for my 10" mirror.

[Tiny Small]

Don't use ethanol. Just water and washing up liquid.

[estwing]

You'd be surprised how dirty mirror get before it starts to affect viewing

[Scott]

From Sky at Nights very own Doctor

[Jaydippy]

Cheers for the advice all, soapy water it is then. Estwing, I'll try and post a photo of it in a sec, it looks fairly dirty but then again I've had nothing to compare it to. 

Certainly going to have to work on my "gently does it" technique...I suffer from (very literal) heavy handedness. 

[DRT]

I used the temid water and washing up liquid method on the primary of my 150 Newtonian yesterday as it was very mucky and I have noticed that the dirtiest parts of the mirror were misting up very early in viewing sessions. I didn't have any distilled water so gave it a very gentle wipe over with Baader cleaning fluid at the end to remove any residue from the tap water. It seems to have worked a treat and I had some lovely views of the moon last night and was able to achieve sharp focus on a few stars just to check that all was as it should be.

One thing that astonished me was that despite the fact I had removed the mirror from the rear cell and then re-assembled it the scope was in perfect collimation when I put it back together. I'm assuming that was beginner's luck!!

My 12" Dob is getting the same treatment today.

[alan potts]

In my opinion we all clean things too much especially eyepieces.

Alan

[DRT]

In my opinion we all clean things too much especially eyepieces.

Alan

I have no scientific basis on which to say this but I suspect that hobbies such as ours attract more than their fair share of those who show Obsessive Complusive tendancies

[Qualia]

There's an interesting and on going discussion about this here which might be of some interest.

My own approach is one not grounded on laziness or disregard but more on a principle of care.  The simple rule being "Do No Harm" and you can't really do harm to optics if you don't clean them. Try not to clean telescope optics or eyepieces unless it is really, really necessary.

[SW130p]

I cleaned mine using the simple rinse with a drop or washing up liquid, came out nice but I would rather clean it with light dirt than wait till it gets thick and harder to get off, that would more likely to damage the surface.

Sent from my iPhone using Tapatalk

[DRT]

My 12" Dob is getting the same treatment today.

Done!

I can appreciate why many will think it unnecessary but I do like to work with clean equipment and doing this enabled me to remove what looked like decomposed insects from the surface coatings, which makes me feel better even if it has done nothing to protect the coatings in the long term. It has also been an educational exercise as I now know how these beasts are put together.

[alan potts]

I have no scientific basis on which to say this but I suspect that hobbies such as ours attract more than their fair share of those who show Obsessive Complusive tendancies

Derek,

I have them too but mine are solely directed to the buying, I do look after my equipment though but like Qualia only clean when absolutely necessary. Take the LX 12 inch, I have had it 7 years I think and I have cleaned the front collector twice and I could not tell the difference at all but my it looked better.

Alan

[DRT]

Derek,

I have them too but mine are solely directed to the buying, I do look after my equipment though but like Qualia only clean when absolutely necessary. Take the LX 12 inch, I have had it 7 years I think and I have cleaned the front collector twice and I could not tell the difference at all but my it looked better.

Alan

The only real difference I have noticed so far is that I could see even more wrinkles when I looked directly into it after cleaning