Cleaning mirrors

[No-i-dear]

I'm having fun with my second hand scope (when I can see something through the clouds that is). I noticed that the primary mirror is covered with a fine layer of dust. It does not seem to bother the image much but I'm just wondering at what stage should I consider cleaning the mirror? Is there a tutorial for doing this on SGL?

Thanks!

[No-i-dear]

Doh! forgot to say my scope is a 6" Fuller reflector (you probably guessed the reflector bit though!).

[Steve Ward]

Unless it's extremely filthy leave well alone .

[cotterless45]

Have a look down the tube , if you can't see yourself, it's time to clean. Just think of it as the last resort,

Nick.

[foundaplanet]

Have a look down the tube , if you can't see yourself, it's time to clean. Just think of it as the last resort,

Nick.

Nice one..

That's about it really, mirrors still perform well in what a state that a lot of folk would probably consider very filthy.

[Carbon Brush]

Leave well alone.

One night I was looking at some close stars. After swapping eyepieces, etc I went back and decided the view was not so good. Looking skyward I couldn't see any difference. Looking at the mirror, it was dewed up as a bathroom mirror.

What I'm saying is that a mirror has to be really really really bad before you get significant image degradation. Add to that cleaning is risky.

[glowjet]

If it comes to the point that you cannot can not live with it, there have been quite a few threads on cleaning mirrors, but basically blow off any grit with an air brush/blower, soak in warm water and a few drops of good quality washing up liquid. if there is any stubborn dirt use soft cotton wool balls, then with a very light touch gently work in a circular motion from the centre outwards and discarded after one pass for a fresh piece, until all is clean. After rinsing in clean tap water, a thorough final rinse in deionised water is recommended and leave to drain and dry in an upright position. All should be ok unless the atmosphere has eaten into the mirror coating with long term storage, especially if it has been kept outside

John.

[Moonshane]

agree with others. I clean only when selling usually or if there's a spot of mould on a new scope (used of course).

you can actually clean a mirror pretty well without even touching the surface.

1) remove mirror from cell

2) use a shower head and luke warm water rinse off the the mirror in the bath (put it on a towel leaning against the side of the bath)

3) if still a bit mucky, soak in a bowl of luke warm water and a bit of washing up liquid (just a few drops)

4) swish the water about without making contact

5) repeat step 2)

6) rinse off with RO water from an aquarium place or distilled water if you can get it.

7) use a bulb blower to blast off as many drops as possible

8) allow to dry and reinstall mirror.

this will remove all but the most stubborn stains and to get rid of those you risk damaging the mirror anyway.

[umadog]

I do what Moonshane does and it's very safe for the surface. I don't wait until the mirror is filthy because dirt encourages dew and dewy dirt degrades the coating. There was a study a while ago that showed regular cleaning will prolong the life of a coating. You decision as to how often you clean should be based on how confident you are that you won't damage the mirror. With reasonable protocols you should be ok.

[damnut]

HI There,

Moonshane has covered this one. Else if you are still thinking about it ....

Follow these steps :---

1. Make cup of tea.

2. Think about cleaning mirror. If Thirsty goto step 1

3. Goto step 2.

Cheers

[No-i-dear]

Thanks guys, sage like advice.

I think the damnut method is the one I will use for now!