Cleaning a Newtonian mirror

[nellyleelephant]

As above really!

Has anyone successfully cleaned the mirror on their Newtonian reflector, if so, how did you do it?
Mine seems to have got itself a layer of dust (ill fitting dust caps) and now the winter season has gone I thought it would be best to bring it back to its former glory.

Any tips?

[Stu R]

First rule is nothing abrasive, and no circular motions or scrubbing.

I've never had to use anything more than a lens brush on the primary (Nikon one from Jessops if it helps!).

[nellyleelephant]

I've watched a couple of videos that show washing up detergent and cotton wool with a final rinse of distilled water.

I do have a hurricane blower I use on camera sensors, maybe I'll give that a go first.

[Stu R]

Yeah, I was told the same but I'm very apprehensive about using washing up liquid (for the same reasons I am when washing the car). Thankfully haven't got to that stage with mine, the blower / brush thingy has always done me great.

[nellyleelephant]

I'll drop the mirror out Monday and see if a blower makes any difference, thanks.

[nellyleelephant]

For those that are contemplating this potentially scary job, don't worry, it's quite easy!

I removed the mirror from its cell and tried the hurricane blower method, for me it didn't work, the mirror was far too dirty! see below!



So, off to the prepared sink (clean, with a clean towel on the draining board).

I filled the sink with tepid water and a couple of drops of washing up liquid. the mirror was then immersed and left to soak for 5 minutes.

When the 5 minutes was up, the water was drained out, and the mirror was washed under tepid water and placed on the towel at an angle to let the washer drain off.

The sink was then filled with tepid water again (see a tepid pattern yet?), holding the mirror above the water, I gently cleaned the surface with a cotton wool pad. I did the cleaning in single strokes across the mirror, a new pad after each stroke.....applying no real pressure, just using the weight of the cotton wool.

After the whole of the mirror has been cleaned by the cotton wool, it was rinsed with deionised water and left to dry. That's it! I repeated the steps with the secondary mirror too, just to make sure.

Hopefully, you should get something like below!



Fit the mirror, collimate, then the job is done.