Canned-air discharge caused mark on lens. Removal suggestions?

[Dustyman]

Lens is a vintage coated wide field Ektar. Canned-air spit out cold propellant and caused a small round spot dead center. I tried ROR, Naptha, even Windex, using Pec Pads.
Please, no scolding about canned-air. Learned my lesson.

Anyone have luck removing similar coating stains?

[Pfsor]

It is not a spit out propellant but very probably a cold damaged coating. Live and learn! You will not see any effect on your pictures, if that is some consolation.

[Dustyman]

Thanks for responding, Pfsor. Yes, I figured it wouldn't cause an effect on the images. But it would be nice to remove, if at all possible, on an otherwise very clean piece of glass : )


It is not a spit out propellant but very probably a cold damaged coating. Live and learn! You will not see any effect on your pictures, if that is some consolation.

[Pfsor]

It cannot be healed and if you removed it, it would remove the coating itself, hence out of the frying pan to the fire...
But again, if of some consolation, you're lucky not to have broken the lens itself...

[Bernice Loui]

That "Canned Air" stuff is BAD for optical coatings. Not recommended:

"Do not use any of the optical spray cans containing pressurized liquid air. The pressurized air from these sprays leaves a slight, but difficult to remove, residue."
http://zeiss-campus.magnet.fsu.edu/articles/basics/care.html

^Above are optics cleaning recommendations by Zeiss Microscopes. Many of the optics cleaning recommendations, materials and procedures apply to high quality imaging optics in general.


Bernice

[neil poulsen]

I wouldn't let one of those canned air containers near my negatives, either.

[Bob Salomon]

That "Canned Air" stuff is BAD for optical coatings. Not recommended:

"Do not use any of the optical spray cans containing pressurized liquid air. The pressurized air from these sprays leaves a slight, but difficult to remove, residue."
http://zeiss-campus.magnet.fsu.edu/articles/basics/care.html

^Above are optics cleaning recommendations by Zeiss Microscopes. Many of the optics cleaning recommendations, materials and procedures apply to high quality imaging optics in general.


Bernice

It is bad for lots of things, including your health! And since it is pressurized it is not allowed by TSA. It is a HazMat and has special shipping requirements! Just get a Giotto Rocket Blaster.

[Alan Gales]

The best way to clean a lens is not to get it dirty in the first place. I've always kept quality clear filters on my lenses and cleaned the filters when necessary. Of course even then you will have the occasional dust speck when changing filters.

I bought a set of 5 Zeiss lenses for my Contax camera back in the 80's. I sold the lenses a few years ago to fund my 8x10 Wehman camera. The Ebay buyers couldn't believe how nice the coatings were on the old lenses. I know, some will argue that a clear filter will ever so slightly degrade the image. I've never noticed that. Besides, those same people think nothing of using a polarizer or colored filters when shooting b&w.

[Mark Woods]

I keep a tank of Nitrogen in my darkroom for both lenses & negs (pressure set at 90 psi). Works great, never had a problem.

[Drew Wiley]

I use a small oilless air compressor (a good quiet one that runs cool - not a revved-up overheated screamer) with in-line micro-filtration. Canned air is expensive over time and potentially risky if any propellant gets out.

[Dustyman]

Drew, which compressor are you using?


I use a small oilless air compressor (a good quiet one that runs cool - not a revved-up overheated screamer) with in-line micro-filtration. Canned air is expensive over time and potentially risky if any propellant gets out.

[Steven Tribe]

I find this an interesting phenomenum! The chemical making up the coating is pretty simple and the only explanation I can think of is that the coating's physical structure has been changed by low temperatures to a more granular (opaque) phase. If it is just absorption of a solvent, then, perhaps, gentle warming will excite the molecules enough to leave the surface!

[Drew Wiley]

Well, I had the unusual advantage of both distributing compressors, among many other kinds of equipment, and having enough clout with manufacturers to be involved in their design. I personally have several small, quiet, oiless, low RPM Thomas compressors made in the US. These are no longer made, although their pumps per se are still available for industrial in-line applications. What you DON'T want is one of those loud cheap "hot dog" units like roofers use because they run hot and therefore condense a lot of water and wear out prematurely. A counterproductive trick to reduce the noise is to clad the unit with a clamshell of thick plastic, which is worse because it traps heat and doesn't allow the pump to cool well at all. It's routine to encounter poorly designed compressors which run at unrealistically high RPM's to produce more air from a more rapid piston motion, and then are labeled with ludicrous phony horsepower ratings, which they term "developed" horsepower. Don't fall for it. Before I retired, the best small compressor I could find as a replacement for Thomas is, alas, made in China, but uses two low-RPM pistons, cools efficiently, and is almost as quiet as a refrigerator. Rol-Air of Wisconsin imports them as their JC10 model. I had a couple minor problems with leaky fittings, but no pump issues.

[Dustyman]

Ok now THAT'S an interesting idea. The same concept is used to remove a water stain from fine wood furniture. I might try this on the lens with a hair dryer!





I find this an interesting phenomenum! The chemical making up the coating is pretty simple and the only explanation I can think of is that the coating's physical structure has been changed by low temperatures to a more granular (opaque) phase. If it is just absorption of a solvent, then, perhaps, gentle warming will excite the molecules enough to leave the surface!

[Paul Ron]

Clean it with denatured alcohol.

[Steven Tribe]

Ok now THAT'S an interesting idea. The same concept is used to remove a water stain from fine wood furniture. I might try this on the lens with a hair dryer!

I wouldn't do experiments on a coated lens you treasure!

Perhaps someone could induce the same effect of canned compressed air on an orphan coated lens or a damaged lens and investigate possible solutions? A look down a powerful microsope might give some clues! Single versus multi-coating?

[Two23]

My advice is to buy a Rocket Bulb and use that.


Kent in SD

[pchaplo]

I’ve had this happen several times. I cleaned it with Panchro lens cleaning solution (used on Panavision lenses) on a Scotch microfiber lens cloth. YMMV.

177412

[Bernice Loui]

Resist the temptation to clean lens surfaces often. Each time this is done runs the risk of damaging the coating or scratching the glass. There is also the problem of stripping off the optical coating with cleaning. This is not likely visible, but could be happening at a microscopic level.

For lenses that can accept a front UV or protector, do this. If not be very, very careful to keep stuff off while using the lens.

Small particles of dust or similar is NOT likely going to affect image quality. Greatest risk for coating and glass damage is when these particles that are always on the optical glass is rubbed-ground into the optical glass by cleaning. Blowing stuff before cleaning helps, but does not always get all the microscopic goo. I'm not convinced those micro fiber lens wipes are good as they can hold abrasive dirt waiting to be ground into the optical glass to be "cleaned".

Disposable Kimwipes are likely a better choice. High purity aka Regent or Electronics grade Isopropyl alcohol is one of the most common lens cleaning solvents in the microscope/optical industry. The other is Acetone if the associated lens components can tolerate it.

Here is another on cleaning optics:
https://www.abelcine.com/articles/news/company-news/abelcine-tech-tips-for-cleaning-handling-and-storing-cine-lenses



Bernice


Bernice

[consummate_fritterer]

I can't remember the last time I had a problem with this. Perhaps it was twenty years ago. I always expel the first ten percent of a new can. Yes, I waste the contents. Otherwise, the slightest angle away from absolute vertical orientation results in greasy expulsion. When the can is warm again, I use it very carefully, ensuring I hold it absolutely upright and flush it first aiming away from the lens. When I'm completely sure no scum is exiting the nozzle, I spray the lens. No problems here.

[Naej]

A few years ago, I bought a air blower that has a Hepa filter. Like this one on this picture (taken from Amazon):
https://images-na.ssl-images-amazon.com/images/I/41KxZdLA5LL.jpg

I chose this kind especially because of the filter, to make sure that no dust will be on camera, the lens or the negative (when working in the darkroom).

What I also like with this kind of blower is that it's safe for the environment (and for the health), and it uses the ambient air so no "cold spots". ;)

Have a nice day!!!
Jeff