clean mirrors

[todd8137]

hi all,well i spoke with a guy on the phone today from a company that re -silvers mirrors i told him i had got a dirty mirror and would like it re coated he then asked me if i had tried to clean it because at around 140 quid its cheaper to clean it

so he told me this ,this is how we clean mirrors before we send them out ,"we use every day washing up liquid and bpc cotton wool nothing fancy just a quick wipe with it then rinse with distilled water and dry with a high speed fan to blow all the water of ,he said a good hair dryer on full power would do the same .he also told me all skywatcher newtonian scopes have a clear coat of resin on all there mirrors so they "can be home cleaned" they do not print this, as they want you to send your mirrors to be cleaned ,and its easier for them wit the resin coat on

i am not gona clean it yet as its not make in any dif to my viewing.

so all this talk of scratching mirors is not that bad ,unless you are heavy handed or in a nervous disposition

[Uplooker]

Interesting, depending on how dirty the mirror is, you should be able to blow the majority of the dirt off with a bulb blower. Certainly do this prior to cleaning. i would also suspect that a lot of dirt would disipate just with the application of slightly soapy water - i would certainly not rub the mirror.

Ian

[David Smith]

I don't have a Skywatcher scope and never heard the bit about resin coating before? Personally I have cleaned the primary on my Revelation scope a couple of times since it arrived (~6 years old now). I followed an article I found on Sky and Telescope magazine web site (can't find it now) but is basically the same as what you have described above except that I left the mirror to air dry whilst stood on edge.

It can be done successfully relatively easily but it is recommended that you do it infrequently as each time you do it you risk damaging the surface of the mirror.

David

[Cornelius Varley]

Taken from the OVL website

"SKY-WATCHER DELUXE MIRROR COATINGS

Most reflectors today usually have a coat of aluminium as the mirror surface and then an overcoat of silicon monoxide or silicon dioxide to protect it. Silicon dioxide produces a much more durable coat than silicon monoxide but requires specialized equipment to apply it and is therefore more expensive. Protection is needed, because in most reflectors, the mirror is open to the elements and deterioration of the reflective layer reduces the resolution of the telescope. ALL Sky-Watcher reflectors are Multi-Coated with Silicon Dioxide as standard for Optimum Durability and Long Term Performance."

Skywatcher mirrors are coated as are most, if not all, newtonian mirrors. The coating protects the silvered top surface.

Peter

[Moonshane]

I agree you should always be careful when cleaning mirrors and avoid it if possible (there's not really any major benefit for almost all observing) but washing up liquid in small concentrations and cotton wool is the standard method of cleaning, with a last rinse with distilled water as you say. if you scrape dirt/grit across any coatings you'll risk fine scratches which scatter light and the effect of all those anti light scattering measures like flocking etc will be reduced.