Your Mirror cleaning tips....

[Tony Leece]

Not sure if this topic has been covered.
But i would like to know your tips and processes for cleaning Newtonian mirrors.
Many thanks in advance guys :thumbsupmate:

Tony.........

[Radar]

G'day Tony, doing a tutorial for this subject at the moment. But here goes,

Use surgical gloves for handling the mirror. Once the mirror has been removed from the telescope, place it on a tea towel in the sink, under a tap with running water. Leave it there for a few minutes. Rinse the mirror with distilled water afterwards. Place back into the tube.

If there are stubborn marks on the mirror, use a cotton wool bud to clean them with, then rinse with distilled water again.

Ray

[Tony Leece]

Thanks Ray.
I have read that a solution of distilled water and isopropyl alcohol and lint-free cotton wool can be used to good effect for cleaning.
Have you tried using this technique?
Also, where would one buy distilled water from? can distilled water used to top up car batteries be used?
Thanks mate........
Tony.........

[Xunil]

Hi Folks,

Just got back from an evening's obs with the new scope, and found that i'd not noticed the buildup of dew - my scope was sopping, so I packed it up, got it home and let it dry. All seems fine, but on closer inspection the mirror is filthy - it looked ok in daylight, but now I've shone a torch down it looks like theres a layer of grime on the mirror - lots of little spots and suchlike too.

Tbh, I'm fairly scared of damaging this vital part - the views I got of jupiter were pretty good, I could just make out cloud bands, took a look at some clusters and got my first view of the dumbell cluster - if this is the case, do i need to clean the mirror, even though it looks so dreadful?

Ray - you mention running water - you mean a rinse under a cold tap, running slow? Sorry if these questions sound dumb, I want to get this right if I'm going to do it.

Thanks!

Tel.

[AstroTasmania]

Hi,

There are many techniques for cleaning aluminised mirrors, some do depend on the type of protective coating applied over the aluminium. Raw unprotected aluminium lasts no time at all, it oxidises so fast when exposed to air. During the coating process, which is done in an airless vacuum chamber, the mirror is flashed with a protective layer of MgF2. On mirrors that are made to order they can be overcoated with quartz (Silicon Monoxide-SO2) instead, which is very much tougher and scratch resistant but double the cost, so it is not done routinely on general amateur scopes.

Give that my mirrors are all quartz coated, I clean them by soaking in clean water with a few drops of teepol/ washing up liquid, which helps to dissolve/soften the fine film of greasy airborn hydrocarbon deposits which come from diesel engined vehicles etc. I also swab with sprayed on Windex followed by a several water rinses.

After a 15 minute soak I then swab lightly with cotton wool balls and work from centre to edge, once, using a new swab for each pass.

A rinse off with tap water followed by a rinse with distilled or deionised water which has one drop of teepol or PhotoFlo(used as a wetting agent for dryinh film without leaving drying marks - ONE drop only in a sink of water) added to reduce surface tension, and the water leaves the mirror in a complete film instead of little drops being left on the surface. Finally, stand the mirror on its edge on paper towel which will draw the water off the mirror.

That is a basic technique, there are many, many others involving the use alcohol, acetone, ether etc in various types & combinations, but it needs some experience. I have been cleaning expensive professional optics all my working life, so have been fortunate and gained considerable experience from Zeiss & Leitz optical engineers in these techniques.

If you do not have good quality tap water, make it a quick rinse and soak in distilled water, bottled water, K-Mart etc. Adelaide tap water eats aluminium while you watch it-!!
A Google search will come up with an extensive range of techniques to suit all levels of experience/expertise.

Clear skies...

Shevill

[Xunil]

Thanks for the advice Shevill :)

Looks like my mirror was just misted up. Took another look a few mins ago, noticed the mirror was looking clean again on one edge, so left the tube on its side with the cap off so dust settling wouldn't get such an easy job dropping down the tube and after just a few minutes the mirror is clear again.

I guess I need to get a handle on watching for signs of moisture when I'm out.

I was hoping that the Newtonian design would act as like dew shield - which I thought was just a tube - looks like I haven't got a clue! Still, learning every day. I'm guessing that the spots I could see while the mirror was dewed up mean that it could do with a clean anyhow but I'm too terrified of the job for now! What a wimp eh? :D

[AstroTasmania]

Hi Xuntil,

Many people worry unecessarily about dust and spots on their mirrors, if it is a new telescope it should not need cleaning for a long time, especially if it is covered when not in use. When it mists up, allow it to come to room temp on its own and dry off, lay it on its side to stop bits falling on the surface. Some people use a hair dryer, but this needs to be done with care, on low, well away from the mirror, personally I have never bothered doing this. A matter of choice, I have seen bits of hot air element let go and splatter on the mirror surface!!

I have just cleaned my SN-10 optics after 5 years use!

Clear skies...

[orion]

Living on the coast I tend to wash the mirrors more frequently because of the salt air. My mirrors are quartz coated and I use the technique that Shevill describes.

Don't be scared to wash your mirror if it needs a wash as long as you do it the right way.

[Tony Leece]

Sound advice, thanks guys :thumbsupmate:
I think those of us who have not had the experience, are scarred to death of going anywhere near our optics.
Especially when a careless hand could cause expensive damage to them.
I feel much more confident now :Chessy_Smile:
Will give it a go this week, as i'm on holiday and will be sorting out my kit.
Thanks again and all the best........
Tony..........

[rmcpb]

Xunil,

Never use the torch down the OTA as a test for cleanliness of the mirror. Even a mirror you have just cleaned will look grotty with that test. If you have looked at it in daylight and it looks OK leave it.

Cheers