Cleaning dust off the mirror

[freelander86]

My Newtonian reflector has a couple of large dust spots on the mirror.

I can see them easily from the open end of the tube.

Does anyone have any simple ways to clean it?

I was thinking of blowing somehow but our air compressor usually pushes out alot of moisture too!

[Kevdan]

Hi,

You can buy blowers from FLO, if it is only dust then this will clear it, but it's unusual to have dust build up in one spot or another, dust usually is even across the mirror, if it is something else then the mirror may need to be removed and cleaned, there are several you tube videos on how to do this, and remember it will need collimating when replaced.

Just thought get a can of air duster from a stationary shop that cleans keyboards etc.

Kev.

[Tiddles]

Mind out!! The propellant from canned air can leave a deposit on the mirror/lens far worse than what you were trying to remove.

[umadog]

I use a rocket blower. No propellant: just squeeze the bulb.

[jkemal]

Are there any telescope mirror cleaning sets available to buy?

[Chris H]

Personally I'd leave it. I would have thought it will have no impact on the views the telescope produces.

[Moonshane]

there's unlikely to be any detrimental effect to the visual observing with dust on mirrors. if you want to have a go at cleaning it then an easy way is as follows:

take out the primary and leave it in the cell.

use a dust blower first, being careful not to hit the mirror with the end.

if this works put the mirror back. if not then put the mirror in the bath (empty!) and use a warm shower head to rinse off for a minute or two. not generally a need to touch the mirror with anything.

then rinse with lots of pure water (not tap water - I use RO water from the aquarium shop) and dab off any stubborn drips with the corner of a tissue. once relatively dry put the mirror back and collimate.

[kenmyers]

My mirror is covered in dust, litterally covered. Got it out of the attic a day ago (4.5" f600) and am shocked at how dirty this is. It is uniformly dirty.

Is their a way to clean it without taking out the cell from the tube?

I was temped to take out the cell last night and use water but am worried what to do if the dust doesnt come off easily as it is totally covered.

...alas I hadnt realised I shouldnt use tap water. Good job I read this first.

I love this forum.

[Moonshane]

sorry, just to be clear, I meant don't use tap water for final rinsing. I use a standard bath shower head for the washing with standard warm water.

you cannot really clean the primary without removal unfortunately. if it's really bad then let it soak for a bit in warm/tepid water and then shower off / final rinse.

[assasincz]

I actually cleaned my 4.5" newtonian's primary mirro just days ago, because it was covered with dust and mineral deposits from condensed air moisture.

First, I removed the mirror cell from the tube and then removed the mirror itself from the mirror cell. Then I placed the mirror carefully in a sink and let warm water pour on it for five minutes or so. Having washed my hands really thoroughly, I then sprayed a little Mr. Muscle window cleaner on it while it was still wet and rubbed the surface softly with my fingers, as per various video tutorials on Youtube. Then, I put the mirror in the sink again and let water pour on it for a while. Finally, I rinsed the mirror with distilled water left it leaning against a wall at an angle to let it dry. The mirror is crystal clear now with no signs of schrathing or anything - works a treat.

[freelander86]

I managed to do it quite easily in the end... but had to carry my scope to an air compressor!

Dropped the pressure down and then stuck a lance half way down the scope. Very quick blast took everything off!

[Chris H]

I managed to do it quite easily in the end... but had to carry my scope to an air compressor!

Dropped the pressure down and then stuck a lance half way down the scope. Very quick blast took everything off!

Has it made any difference to the views?

[freelander86]

Well for me it was less dust and more one particular large spec... so for me yes it has improved the image because it was apparent on photos I had taken!

It can only help though to keep things clean

[pat]

I've heard you can leave the mirror in the cell when washing it. Then use a hair dryer. Pat

[heathenwoods]

My scope is a fairly battered old Tal and the glass needed 19 years of accumulated dirt and 'stuff' clearing from it. I found this pretty comprehensive guide invaluable - it may be for Tals but should be applicable to most reflectors.