Cleaning secondary on dobsonian

[wiseman]

I have managed to get a finger marks on my secondary trying to juggle a heater element onto the stem.

The Baader magic cleaning fluid says " NOT for use on Newtonian mirrors".

So far someone has suggested using aceteone.

Any other suggestions please, as I dont want to make it worse,

Cheers

Wise

[umadog]

I have used acetone to get rid of stuff like that. You can try just washing the acetone over the surface. Get the pure stuff with no significant impurities. Perhaps it's a good idea to first wash the surface with deionised water. Just pour the stuff over the surface and let it air dry. Be careful the acetone doesn't come into contact with plastic!

Do not use a cotton ball at all. I've looked at a secondary through a 20x microscope and regions which have been physically cleaned have scratches in the coating. These won't affect the views, but if you keep cleaning it this way there'll be problems.

[TheThing]

Steppenwolf has an excellent video tutorial about cleaning mirrors. All he uses is water, a drop of washing up liquid, cotton wool and deionised water to rinse.

Works a treat!

[damnut]

Hi please do not use pure acetone, its very aggressive!

A couple of drops of iso propyl alcohol (lens cleaner, cd cleaner etc) in a small cup of water to wash the gunk off then as above with warm water and a drop of wup liquid.

Good Luck!

[xyz]

Unless the finger marks are really large and really smudgy you take a risk trying to clean it. I think you will be surprised at how grubby a mirror can get before you notice a real drop-off in performance.

[wiseman]

i called telescope service and her is what they said.

use dishwasher detergent ( liquid, not solid tablets).

put some in a bowl of water. put the whole secondary in it for two mins, then rinse it cold water, allow to dry.

evidently the skywatchers have coated mirrors so they can be rubbed a bit if nesc with something gentle, but this method is best.

I will give it a try.

more news as it happens

[Nexus 6]

amazing what you find out on here, dishwasher liquid can clean up a scope mirror. Hope you get it straightened out wiseman

[LukeSkywatcher]

I wont even tell you how i once cleaned my secondary while outside and i got a fingerprint on it. Lets just say that the mirror is fine and no lasting damage was caused.

God bless soft cotton t-shirts.

The day my primary needs cleaning...................i'll just buy a new scope. It will be less worrying.

[umadog]

Don't use the cotton wool. There really is no reason to do so if the cleaning agents do their job.

Yes, acetone is aggressive, it dissolves plastics and other organic stuff but it won't hurt mirror coatings. Plenty of people use it all the time. I've heard it's not a good idea on lens coatings, but that may be because a lot of lenses are surrounded by plastic.

[stolenfeather]

Just thinking about cleaning my mirrors makes me shake within! Come to think about it, it wasn't that long ago when simply collimation made my knees feel weak! Dishwasher liquid really? Wow! I would never have thought!

Isabelle

[JohnnyD333]

Steppenwolf has an excellent video tutorial about cleaning mirrors. All he uses is water, a drop of washing up liquid, cotton wool and deionised water to rinse.

Works a treat!

I agree, I used the method on this youtube video and it worked great.