Cleaning primary mirror

[Littleguy80]

I’ve noticed the primary mirror is looking quite dirty so it’s probably time to brave cleaning it. As I haven’t attempted this before I’d appreciate tips/advice on best approach to do this without damaging the mirror or coatings. 

Thanks in advance!

[Owmuchonomy]

This is good: http://www.skyatnightmagazine.com/feature/how-guide/how-clean-reflector-telescope-astronomy

[Stargazer McCabe]

Don’t be apprehensive. Plenty of pure, distilled water, adequate supplies of cotton wool, careful planning, a clear and clean working area and time on your side.

I’ve done my 14” and wondered why I’d been so concerned about it after I’d done it...

It really is a simple process and nothing to be anxious about 

@steppenwolf and others have some great videos on YouTube 

Happy viewing 

[Littleguy80]

6 minutes ago, Owmuchonomy said:

This is good: http://www.skyatnightmagazine.com/feature/how-guide/how-clean-reflector-telescope-astronomy

Perfect. Thank you  

[Littleguy80]

1 minute ago, Stargazer McCabe said:

Don’t be apprehensive. Plenty of pure, distilled water, adequate supplies of cotton wool, careful planning, a clear and clean working area and time on your side.

I’ve done my 14” and wondered why I’d been so concerned about it after I’d done it...

It really is a simple process and nothing to be anxious about 

Thank you. I remember being the same way about collimation, particularly adjusting the secondary. After I was done, I realised it was no big thing  

[Alien 13]

Not sure if its mentioned in the videos but a clean tea towel on the work surface is useful to prevent the mirror slipping/sliding to an expensive accident.

Alan

[Littleguy80]

11 minutes ago, Stargazer McCabe said:

@steppenwolf and others have some great videos on YouTube 

The scope in question once belonged to @steppenwolf  

[Littleguy80]

In fact it looks like the very same telescope that’s being cleaned in article above! 

[steppenwolf]

45 minutes ago, Stargazer McCabe said:

 

@steppenwolf and others have some great videos on YouTube 

Here is my video

33 minutes ago, Littleguy80 said:

In fact it looks like the very same telescope that’s being cleaned in article above! 

.....and it is indeed your reflector that is detailed here - the one and only clean it has ever had!

[Littleguy80]

Thanks Steve. Can’t ask for a better guide than that  

Question on distilled water. I have some De-ionised water which a quick Google suggests should be just as pure as distilled. Is that ok to use? 

[scarp15]

Not a task that requires to much frequent attention, I soak mine, lying flat, in a small children's inflatable paddling pool, using distilled marine, which I obtain from a local Garden Centre. I then drip dry upright, which can be further dried with a cold blow setting hair dryer. If you have spare water (usually obtainable in 5L reusable containers), store in cool dark location for future use. I had once used the cotton wool ball process, applying no pressure just lifting off the surface once soaked. Here's a picture of the paddling pool.

 

 

[Sunshine]

I have been told by many experienced dob owners that cotton balls are out and finger tips are all the rage now, clean finger tips.

[steppenwolf]

11 minutes ago, Littleguy80 said:

Thanks Steve. Can’t ask for a better guide than that  

Question on distilled water. I have some De-ionised water which a quick Google suggests should be just as pure as distilled. Is that ok to use? 

Now that, Neil  involves worms, can, open and a in a different order!! I believe that you should only use Distilled Water and I personally wouldn't use de-Ionised, reverse osmosis, fish tank stuff etc. despite what others say BUT that's just me! ?

I have opened the popcorn ......

[Littleguy80]

1 minute ago, steppenwolf said:

Now that, Neil  involves worms, can, open and a in a different order!! I believe that you should only use Distilled Water and I personally wouldn't use de-Ionised, reverse osmosis, fish tank stuff etc. despite what others say BUT that's just me! ?

I have opened the popcorn ......

Haha oh blimey. I didn’t realise it was such a controversial question. It doesn’t look too difficult to simply distill you own water from tap water.

https://www.google.co.uk/amp/s/m.wikihow.com/Make-Distilled-Water%3famp=1

I tried a couple of places this afternoon and deionised water was the closest I got to distilled water 

[Stargazer McCabe]

1 minute ago, Littleguy80 said:

I tried a couple of places this afternoon and deionised water was the closest I got to distilled water 

 

I got my distilled water delivered next day  from Amazon...

[scarp15]

The cotton wool ball approach really is non essential unless there are blemishes, even then. Surgical cotton is recommended, standard ought be fine but as said if I were to repeat I'd use my finger tips, main rule of thumb is to apply no pressure. 

[Uplooker]

43 minutes ago, Sunshine said:

I have been told by many experienced dob owners that cotton balls are out and finger tips are all the rage now, clean finger tips.

I agree wholeheartedly with the above.

31 minutes ago, steppenwolf said:

Now that, Neil  involves worms, can, open and a in a different order!! I believe that you should only use Distilled Water and I personally wouldn't use de-Ionised, reverse osmosis, fish tank stuff etc. despite what others say BUT that's just me! ?

I have opened the popcorn ......

RV water for me too ?. Any tropical fish retailers, only about £0.50 for 5 ltr

[Ricochet]

After you've soaked the mirror check that the centre spot hasn't lifted and moved. 

Other than that just follow the video linked previously. 

[Alien 13]

Proper distilled water (at least six times through the loop) is as rare as hens teeth at an eye watering price but its the only stuff I would use.

Alan

[Littleguy80]

9 minutes ago, Alien 13 said:

Proper distilled water (at least six times through the loop) is as rare as hens teeth at an eye watering price but its the only stuff I would use.

Alan

I was looking on Amazon and thinking the prices were expensive for water but sounds like not!

[Stargazer McCabe]

12 minutes ago, Littleguy80 said:

I was looking on Amazon and thinking the prices were expensive for water but sounds like not!

When one thinks of the value to us, let alone the actual cost, of our primaries; is it really that much..??

[Littleguy80]

11 minutes ago, Stargazer McCabe said:

When one thinks of the value to us, let alone the actual cost, of our primaries; is it really that much..??

Very true. Something like this fit the bill?

Distilled Water - 5.5 litres - Ultra Pure Water https://www.amazon.co.uk/dp/B0765CQDQD/ref=cm_sw_r_cp_api_xX03BbS47M335

[Stargazer McCabe]

That’ll do nicely... 

[steppenwolf]

This is where I bought my distilled water from so the Amazon price looks a little expensive? However, this needs to be tempered with the fact that I didn't use anywhere near all of my 10 litres as it is only used for the last rinse(s). I still have it in stock carefully stored for the next clean ......oh, hang on, I no longer have my 10" reflector ....... ?

[Carbon Brush]

A thumbs up for the Steppenwolf cleaning technique and tips.

I have used deionised water without problem. My final rinse being a mixture of water and isopropanol.
This reduces surface tension (gives a uniform wet coverage) and dries without marks.

But of course, is the mirror really really really dirty? Can you leave it for another day?

David.