How do you clean an oil painting?

I“ve only heard of it being done professionally but I would use a damp cloth . A very soft , barely damp cloth.

Unfortunately hair spray doesn’t really stick to objects in layers, it kind of just lands everywhere, so in theory there are levels of thickness of hairspray all around.
An oil painting is well, is oil based, so also there are levels of more or less concentration as it is layed out. So imagine there are tons of “hills” all around the painting. As well as perhaps little, “caves” from the turn of the strokes or a heavily concentrated area. Any who, simply dusting it off with some sort of duster is fine. Since you said it’s cheap, it could be made from factory vinyl. I would then just wash it down, test a spot. With hot water, choose a corner and if doesn’t melt off (run oil in the water) then it is fine.

OK, this sounds strange, but this article recommends using doughy bread.

There are many methods for doing certain things to an oil painting. Work is usually done by a professional though. If this painting is not too valuable and you wish to try to clean it yourself, I would suggest contacting the Smithsonian Museum Conservation Institute . They may have online courses or a conservator may be able to advise you or point you to some information you can obtain yourself.

Cleaning methods would vary depending on the substrate, the presence or lack of an over varnish and a number of other variables. A conservator formerly at the Smithsonian told me once that among the many techniques employed in a cleaning, a little spit at the end of a brush could remove some small problems, due to the viscosity and slight acidity of sputum.

Wow! this reminds me of a scene from the movie Mr. Bean where he completely destroys Whistlers mother. Definitely don’t do that! Luckily hair spray is mostly dry by the time it floats around and lands on the painting. Laying it flat on a surface and vacuuming it with the long brush thing if you have a canister vacuum could help remove accumulated dust, or simply using a soft dust broom to carefully brush off the accumulations. Being gentle is the key part, and using things that don’t leave their own problems behind.

@majorrich I hope that you are not referring to Stefano Scafetta’s spit.