Really weird one for the braintrust.
 

Lets say you had a large object like a car and wanted to cover it in Talc or similar substance to temporarily knock back reflections.

Substance has to be easily removable as in simply washes or peels off with no residue.

Plasti dip is out BTW.

Should not be something so opaque that it alters or conceals any colors underneath.

Also cost effective, as in cheap, not an arm and a leg, maybe $10-20 to cover a car.

And how to apply?

Maybe something water soluble that can be applied evenly with a garden variety pump sprayer that dries matte?

Automotive paste style wax? Buff off when you are done and have a nice shiny car.

Really weird one for the braintrust.
 

They used to sell, and likely still do a dulling spray for photography. It will just wipe off. We used to use it for some glassware photography and silverware in the background.
It was just a rattle can spray can. I don’t know what was in it, and I never tried it on a car.

Cars that are shipped to O.S. on a boat are covered in a special protective wax that's sprayed on at the factory with an airless gun.
The wax is removed with a solvent of some kind. The solvent is similar to wax and grease remover.
(There was a 930 turbo for sale a few years ago that still had the coating from the factory)

The finish looks dull/matt but it doesn't change the color.

Cosmoline?

Probably yes but I don't know for sure.

This is the car I mentioned earlier.

http://forums.pelicanparts.com/uploa...1572321693.jpg

https://www.motor1.com/news/146848/porsche-911-carrera-rsr-auctioned/

Fuller's Earth? We use that in the studios to simulate dust.

Mud.

Will it be static or will it me subject to wind? Press N Seal would give a cheap, dull finish, but won't stay on in wind. Opaque contact paper would stick on pretty well but might damage the paint or whatever it's sticking to.

A good one. Maybe wash it and let the soap film dry. I expect it would work with the right soap.

Well we are talking photogrametry which is something I highly doubt you know the first thing about.

Dulling spray does not quite cut it here for a couple of reasons.

We use Magnaflux a lot, great stuff but super expensive. I call it asbestos in a can. Can't spray that much indoors and once you coat with it you can't touch or move the object.

Sort of along my current line of thought, can I mix something like maybe flour / water and use an HLVP sprayer.

But something that is not heterogenous like flour. The pressure from the sprayer will likely make it clog.

Should have included this in OP.

Whatever it is has to go on thin and as close to consistent as possible, sorta like a layer of paint. Any inconsistency will show in the final result.

Or a flour sifter? Just dust the whole thing?

Powder coat but don't bake it?

How water soluble is hair spray?
I would do a GOOD test including plastic and rubber, but if it washes off easy, might work.

Interesting problem...acrylic paint that is soap and water washable?


https://www.discountschoolsupply.com/arts-crafts/paint-paint-tools/acrylic-paint-specialty-paint/crayola-washable-paint-gallon/p/3680

Spray on very soapy water, and let it dry?

If you sprinkle flour, go to extreme fire caution mode. Airborne flour dust is very explosive. It could level your building. I would avoid it just because it is so explosive. Like coffee "whitener", just explosive.

<iframe width="791" height="593" src="https://www.youtube.com/embed/yRw4ZRqmxOc" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

They scared themselves with coffee "creamer"

And this is why it's good to ask questions.

Some body shops cover the remaining parts of the car with a clear spray that keeps the applied primer/ paints from adhering from over spray. It washes off. I don't what the name is, sorry. You could google that...…..