Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

Cleaning a telescope mirror a different way

Chris

By Chris
in DIY Astronomer

 Share

Recommended Posts

Chris

Chris

Posted
Posted

Setting up to observe with the Heritage 150P I noticed the primary mirror looked completely dewed up, or at least I thought it was dew! A few minutes with the hairdryer later confirmed that the mirror was caked in some kind of deposit which left it looking like frosted glass. 

It wasn't budging with the hairdryer and it was slowly dawning on me that I would need to clean the mirror!

Last time a cleaned a mirror I used the good old cotton wool and distilled water technique which worked ok but didn't get all the debris off.

I decided to do some digging to see if there were any other methods for telescope mirror cleaning and I read a few comments here and there talking about using your fingers! 

It seems like a bit of a controversial technique, but I can't argue with the results!

I know which method I'll be using in future.  

 

 

 

 

  • Like 2
Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted
1 hour ago, Laurieast said:

Thanks for that. 

What's the reasoning about using so little soap? I would have thought several drops at least.  

That cloth must have introduced more particles of dust etc, I don't see the need for that. 

You could use 3 or 4 drops instead of 1 or 2 and spend a bit longer with the rinsing. The mirror looks practically new using the method above, but I can try using more soap next time and see what difference it makes.

The cloth is of course optional just in case the mirror slips and turns in the water. I didn't want it to slip face down on the bottom of the craggy bowl.   

 

 

 

  • Thanks 1
Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted
1 hour ago, vlaiv said:

Final rinse should be done with distilled water in case your tap water is too hard. Too hard water will leave residue after drying off.

Rinsing with reverse osmosis water worked absolutely fine for me, although I did of course discuss rinsing with distilled. I'm guessing you missed that part of the video vlaiv. I do understand skipping sections, this is a long video : )

  • Haha 1
Link to comment
Share on other sites
vlaiv

vlaiv

Posted
Posted
27 minutes ago, Chris said:

Rinsing with reverse osmosis water worked absolutely fine for me, although I did of course discuss rinsing with distilled. I'm guessing you missed that part of the video vlaiv. I do understand skipping sections, this is a long video : )

Indeed, sorry about that, I just "browsed" thru the video and did not realize that you have reverse osmosis device installed in your house.

That is perfectly fine as well, and main point is of course to let the people know that hard water can leave stains on the mirrors and they should try to use either distilled, demineralized or like in your case - filtered by reverse osmosis.

  • Like 1
Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted
9 minutes ago, vlaiv said:

Indeed, sorry about that, I just "browsed" thru the video and did not realize that you have reverse osmosis device installed in your house.

That is perfectly fine as well, and main point is of course to let the people know that hard water can leave stains on the mirrors and they should try to use either distilled, demineralized or like in your case - filtered by reverse osmosis.

I was intermittently wrestling a giant bottle of RO water that I use for my marine fish tank water top ups 💪😅

 

1.jpg

Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted (edited)
3 hours ago, Alien 13 said:

Have to admit I always used to clean my mirror this way back in the day as you could feel the slightest imperfection/stuck on dust particle, never trusted cotton wool after looking at some with a microscope.

Alan

I bet wool looks like wire under a microscope!

I know what you mean about feeling debris with your fingers. I had read the theory but I was still surprised by how well you could actually feel these! 

Edited by Chris
  • Like 1
Link to comment
Share on other sites
jetstream

jetstream

Posted
Posted
22 hours ago, Chris said:

It seems like a bit of a controversial technique, but I can't argue with the results!

I know which method I'll be using in future.  

Excellent video and technique Chris!

So many think cleaning a mirror is witchcraft IMHO, but in reality its simple safe and effective- your method it top and the one I use (with more soap, spray bottles and Aquafina for the final rinse lol!).

  • Thanks 1
Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted
1 hour ago, jetstream said:

Excellent video and technique Chris!

So many think cleaning a mirror is witchcraft IMHO, but in reality its simple safe and effective- your method it top and the one I use (with more soap, spray bottles and Aquafina for the final rinse lol!).

I was a bit nervous about posting this video as I know cleaning optics can be a bit of a divisive subject, so I appreciate that! thanks :) 

p.s. I had to Google Aquafina...I don't think we have that one over here?  

  • Like 1
Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted
47 minutes ago, Laurieast said:

Chris,

Would CarPlan de-ionised water be suitable do you think? Thinking that as it's cheap and in most supermarkets.

Well de-ionised water has had all the mineral salts removed, so I think it would be fine :) 

  • Like 1
Link to comment
Share on other sites
  • 2 weeks later...
  • 3 weeks later...
Stardaze

Stardaze

Posted
Posted (edited)

Thanks for posting this method. I've just discovered that my mirror needs a clean for the first time, not sure how it's got so dirty literally overnight but I'll need to get it done. 

Edited by Stardaze
  • Like 1
Link to comment
Share on other sites
Chris

Chris

Posted
  • Author
Posted
34 minutes ago, RobertI said:

I used the fingertip method to clean my 130p mirror last night and it worked a treat. Highly recommended. Thanks Chris! 👍

Brilliant! You're welcome, and thank you for trusting my instructions 👍🤪 

  • Like 1
Link to comment
Share on other sites
Carbon Brush

Carbon Brush

Posted
Posted
On 24/09/2021 at 17:34, Laurieast said:

Chris,

Would CarPlan de-ionised water be suitable do you think? Thinking that as it's cheap and in most supermarkets.

An interesting thought. De-ionised means there are no (or few) ions in there.
For example no salt or other compounds that conduct electricity when in solution.
However, clean sand (not salty from the beach), engine oil, heating oil, and many other things do not conduct electricity so are worthy of the name 'deionised'.
So is this pure-ish water, or just not electrically conductive?

The last mirror clean I did used warm tap water with soap & and IPA/water mix for a rinse.
Provided you don't use something like sea water, leave it for hours and hours, and don't let it dry, a few chemicals in the water are OK.
This is drinkable tap water - not something from the roadside or local pond.
Physical cleaning was no more than a gentle cotton swab where agitation was not enough.
At the end, I left the mirror vertical and wet. Then gave it a few squirts with Baader fluid to wash off any remaining chemicals.
It worked out well.

HTH, David.
 

  • Like 1
Link to comment
Share on other sites
Laurieast

Laurieast

Posted
Posted (edited)
14 minutes ago, Carbon Brush said:

Then gave it a few squirts with Baader fluid to wash off any remaining chemicals.

Now there's an idea! Thanks, always have a supply of that. 
Could apply it with the airbrush 🤔

Edited by Laurieast
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.