Clean mirror with compressed air?

[Geoff45]

Has anyone used one of these (or something similar) to get the initial dirt off a primary mirror?
https://www.bunnings.com.au/3-in-one-professional-350g-air-duster_p6100311
Geoff

[Kunama]

Geoff, I think you will find that they don't contain air, rather a highly flammable difluoroethane ...... I have no idea what difluoroethane does to optical coatings.....

[Exfso]

I got one of these and they work a treat. No propellant to do damage, only need to recharge battery. Not cheap, but useful for all sorts of things.

https://www.pccasegear.com/products/31698/o2-hurricane-320-canless-air-system

[astro_nutt]

Hi Geoff.
A bulb type blower like they use for camera lenses, EP's would be sufficient to remove any loose dust particles. Whatever is left behind will not degrade your image.

[Stonius]

I use canned air often - same stuff as they use on film sets with lenses worth much more than most people's telescopes; the trick lies in knowing that the can should be used flat and level and you do a quick squirt away from your optical surface before you use it on your optics. If you know not to tilt and spray, you won't have a problem.

Markus

[Shiraz]

I tried some once and it left a very light oily residue - test it on some glass first.

[el_draco]

The solution Bintel sells to clean optical surfaces works an absolute treat as long as you follow the instructions.

[Geoff45]

Thanks all for the advice. Looks like it will work if used properly, but better to avoid if possible.

[Kunama]

I have used for cleaning electronic componentry but not for optics (yes, I know many people use it for professional movie lenses)
The gas is also quite a potent 'greenhouse gas', one can (275gr) sprayed into the atmosphere is equal to about 35Kg of CO2 :eyepop:

[janoskiss]

A compressor works very well for cleaning dust off a mirror or corrector plate. Just be gentle, do not blast it but use light pressure (air velocity) at first and gradually increase the pressure, taking your time. And don't go nuts over stubborn stains or bits of dust: they will need a wash to move safely.

I've not used a can based blower on optics (only on electronics) but IME it's harder to control than a compressed air gun and the air/gas stream is more focussed (so more chance of doing damage by blowing an abrasive particle across the surface). But you can control it using distance from the surface instead of the trigger like a CA gun. (But in either case also use distance from surface to control how soft or hard..)

I use a bulb blower regularly on eyepieces and mirrors. They are typically gentle enough but not powerful enough to remove as much dust as a compressed air gun might from mirrors.

[Exfso]

Only hassle with air compressors is that they can blow contaminants from tank. I would not recommend for optics. If you are going to blow air it has to be free from any contamination and/or propellants in my opinion, this is why I use the hurricane, it only uses an impeller to generate the high speed air.:)

[Steffen]

Interesting device (if a bit pricey, like you said). How hard do you reckon it would be to add some filter fleece to filter the intake air?

[janoskiss]

Thanks Peter. I did not think of that but I should have. I used a compressed air gun a few times with no mishaps but for sure there is likely to be particulate matter in the tank. Maybe a filtered muzzle over the end of the gun...?

[Exfso]

Steffen, are you referring to a compressor regarding a filter?
Definitely do not need on with the hurricane unless operating it in a real dirty dust environment, it just grabs air from your location and pumps it out at a helluva rate..

[sil]

Hurricane is great, been using one for years. Filters? Silly idea, they will just build up crap until its heavy enough to break free and be hurtled out the nozzle at high speed. Its not like normal dust going through is anything sandblasting your optics but i guess people need to complain about nothing.

[Moontanner]

Watch out for oil as a contaminant in many air compressors. These days I use an oil free compressor for most things and don't really worry too much.
Back in the day I would run an inline sintered filter when spray painting. Spraying will show up contaminants pretty quickly in the finish and it was easy to see the difference the filter made.

If you want a cheap solution from Bunnies I'd suggest using a garden sprayer with a hand pump. A 5L jobby will set you back around $10 and can always be repurposed if needed. Add a thin straw as the nozzle and you're away!:thumbsup:

Environmentally friendly and pretty quiet during a late night refill.

Clear skies!