Cleaning primary mirror.

[Dave scutt]

Hi all .

I would like to clean my primary mirror I'm a bit nervous,   views are still good but it's a bit grubby and when I flock the ota I'll have to take it out anyway. 

Just wondering if this cotton wool would be ok or should I just use my fingers and a dab of washing liquid.  I've already ordered the distilled water.

 dave

[Laurieast]

Have you seen this? 
Just a thought, to help avoid any scratches. 

"There are many videos covering the well founded cotton wool and distilled water method for cleaning telescope mirrors. Here I experiment with a different technique which I now believe is the best way to thoroughly clean a mirror without damage. Please watch in 4K for best results. "

There are many videos covering the well founded cotton wool and distilled water method for cleaning telescope mirrors. Here I experiment with a different technique which I now believe is the best way to thoroughly clean a mirror without damage. Please watch in 4K for best results. If you would like to help towards my partly self inflicted channel expenses you can buy me a coffee her

 

 

Edited June 29, 2022 by Laurieast

[Dave scutt]

Thanks Laurieast.

Very helpful. 

[Craig a]

I’ve always used the finger method with 1 drop of dish soap, always comes up sparkling 

[wookie1965]

I did this with a really dirty 8" mirror came up sparkling I used distilled water had no droplets left and streak free.

[neil phillips]

If you do the finger method be careful. if you feel anything under your finger stop, and do not try to remove it. If you feel anything especially a tiny bit of grit. the temptation is to wipe it away with your finger, but if you think about it that will draw it across the mirror causing a sleek. I personally have gone back to cotton wool for this reason. i can get a much lighter draw with flaky cotton under water and no pressure. But of course you cant feel resistance. But you can get a very light draw across the mirror surface. if really worried let the weight of the cotton and water swill across the surface. thats the lightest way. But may not get it totally clean. But is almost totally safe. 

[Steve Ward]

After forty years working with my hands , mainly in construction , I would never dare try that finger method , my fingers are far too hard and calloused to put anywhere near a front surface mirror.

The chap in the video looks like he's never done anything but tap on a keyboard and wash-up so is probably fine with it ... 🤣

[Chris]

1 hour ago, Steve Ward said:

The chap in the video looks like he's never done anything but tap on a keyboard and wash-up so is probably fine with it ... 

You're not wrong Steve, for the last year I've had a keyboard Job, and I do do the washing up! 

As you say I wouldn't have used this technique back in the day when I was running parts off lathes all day, too many metal swarf splinters!   

If I remember rightly I advice in the video to only use this method if you don't have engineer/mechanics/trades mans hands of leather with metal spikey bits poking out 😅 

 

[PeterStudz]

I work outside and often have very grubby hands. But when I cleaned my mirror I used the finger method.

However, I started cleaning my hands and fingers the day before. I also took the opportunity to have a long bath & clean my hands until they were wrinkly. Then washed them well the next day before I started on the mirror. My hands have never been so baby soft 😀 Although I didn’t spend too long on the actual cleaning (fist time I’ve tried) I didn’t have any issues. 

[ukskies]

As has been said if your hands are anything other than baby soft use the cotton wool.

I cleaned my SW 12" mirror with warm water and dish soap, letting the mirror soak submerged for a few minutes then rinsing off with warm tapwater holding the mirror at an angle to lightly pressure wash any grit particles off without harming the surface. I did this 3 times before I even got the cotton wool out and I did what the vids show and stroked the surface gently without any pressure , just the cotton wool weight against the mirror.

I then finally rinsed with distilled water with the mirror almost standing on its side and gently blotted the final droplets away with tissue, just the corner of the tissue actually.

The finished mirror looked like new.

I have recently tried to clean an 8" Orion Optics mirror which had grit particles seemingly glued to the surface and whatever I tried thet would not let go. The only way to remove them would have damaged the coating so be careful how you decide what is important and what is not. An undamaged mirror with a few grit particles will give a better image than a grit free one covered in sleeks from over zealous cleaning.

Good luck and be very deliberate and gentle.

[Spile]

I recommend the finger tip method. https://astro.catshill.com/mirror-cleaning/

[Craig a]

Hey it is possible to have tradesman hands and not have wrecked skin, I’m a builder but wear thin gloves,cement and plaster destroys my skin, finger meathod all the way, finger tips are very sensitive so you want to feel for dirt, Carnt do that with cotton wool 

[clarkpm4242]

Video is great.  Has many good tips!  I've always used quality cotton wool...let the weight of the wet wool do the work.  14" - 18" mirrors.

Am sure you'll be okay. 

Paul

[Stu1smartcookie]

Dave , how dirty is the mirror ? Lets face it , we've all been a bit paranoid about wanting to clean a scope mirror . I had a scope that had all sorts of mirror issues but it still showed nice bright views and it was almost opaque !!! . I suppose what i am saying is , unless its really impacting on your viewing , leave it alone . Although i honestly can relate to the temptation you feel to clean it . 

[Dave scutt]

4 minutes ago, Stu1smartcookie said:

Dave , how dirty is the mirror ? Lets face it , we've all been a bit paranoid about wanting to clean a scope mirror . I had a scope that had all sorts of mirror issues but it still showed nice bright views and it was almost opaque !!! . I suppose what i am saying is , unless its really impacting on your viewing , leave it alone . Although i honestly can relate to the temptation you feel to clean it . 

I have a new duel speed focuser to fit and was going to flock the tube , so I thought I'd might aswell clean it as it will be coming out.

I think I might have pinched optics aswell when I focus or defoucus for a star test it looks  like a triangle Shape but collinmation looks ok

[Stu1smartcookie]

16 hours ago, Dave scutt said:

I have a new duel speed focuser to fit and was going to flock the tube , so I thought I'd might aswell clean it as it will be coming out.

I think I might have pinched optics aswell when I focus or defoucus for a star test it looks  like a triangle Shape but collinmation looks ok

Seems a good time  to clean it then , Dave.

[Stu1smartcookie]

Might as well chime in with the method i have used ... Cotton Wool Balls in a mild detergent . Spoiler alert ... its sooooo satisfying when you see the mirror sparkiling and the drops of distilled water drying without leaving any residue

 

[iapa]

Make sure the cotton wool is from a well known manufacturer and carries the BP* (British Pharmacopoeia) mark, but note that even then there may still be some husk in the product.

 

* other areas such as India, Europe and Japan have their own equivalent.

[neil phillips]

On 30/06/2022 at 20:08, Dave scutt said:

I have a new duel speed focuser to fit and was going to flock the tube , so I thought I'd might aswell clean it as it will be coming out.

I think I might have pinched optics aswell when I focus or defoucus for a star test it looks  like a triangle Shape but collinmation looks ok

Yep thats pinched. And will likely destroy fine planetary detail. Sort that out and your lunar rills will be hairline. The mirror should be able to rotate in its cell. and when you move the cell around you should feel a very small clunk. as the mirror moves to a new position. Not moving in its cell by rotating. And no small clunk. is too tight. 

[Dave scutt]

On 21/07/2022 at 12:37, neil phillips said:

Yep thats pinched. And will likely destroy fine planetary detail. Sort that out and your lunar rills will be hairline. The mirror should be able to rotate in its cell. and when you move the cell around you should feel a very small clunk. as the mirror moves to a new position. Not moving in its cell by rotating. And no small clunk. is too tight. 

The mirror doesn't rotate and the clips look like they have been done up tight 

[neil phillips]

17 minutes ago, Dave scutt said:

The mirror doesn't rotate and the clips look like they have been done up tight 

If you cant finger rotate in its cell, something is holding or sticking. Sticking is not so bad.

holding is worse.  Is the mirrors height against the 3 top clips adjustable ?

What about how its held side ways. Is that adjustable ?

 

Edited July 27, 2022 by neil phillips

[Dave scutt]

5 minutes ago, neil phillips said:

If you cant finger rotate in its cell, something is holding or sticking. Sticking is not so bad.

holding is worse.  Is the mirrors height against the 3 top clips adjustable ?

What about how its held side ways. Is that adjustable ?

 

Just taken off clips , mirror has just been washed and drying before I put the clips back on will let you know how it goes

[Laurieast]

In the old days we did the clips with a business card under the clip. Push the clip down and tighten the clip screw until you feel the slightest resistance. Pull put the card (should not be tight to pull out).

Edited July 27, 2022 by Laurieast

[neil phillips]

19 minutes ago, Laurieast said:

In the old days we did the clips with a business card under the clip. Push the clip down and tighten the clip screw until you feel the slightest resistance. Pull put the card (should not be tight to pull out).

Just be careful sliding card in or out to check a gap. It can scratch. And is not obvious when your doing it. Just a tiny gap between mirror and clips. And anything holding the primary sideways. Just enough. so the mirror will finger rotate. Is about right. Sliding card or even thick paper under the clips to check the gap is one way to do it. I just feel the gap. and do the rotate test. But either should work. You just have to be more careful with the card trick

[Dave scutt]

Does it matter if the screws on the clips are not tight otherwise I cannot slide a piece of card in between the clip and the mirror.