Simple and cheap anti-graffiti layer based non-paint solvent I have this issue with a group of people intentionally damaging a bench. So far, they would paint curses over the bench with permanent marker. However after I removed the curses with ethanol, they damaged the bench physically and threw the trash all around (we used to have a trash can there, with sign "Please do not throw trash around" - they threw this trash can away too).

I would like to keep this question non-personal though, so my question is:

How can I protect a nitro-based paint layer from other paints?

The professional solutions are way too expensive, while the thing I want to do is simple: I'm looking for non-nitro based material and solvent that will form transparent layer over the original paint. In case of damage by nitro-based paints, I could wash the layer under them and then apply it again.

The theory is following: you apply the protective layer over your paint. When somebody applies any paint over it, you've got 3 layers.



It does not matter what the top layer is, as long as it does not dissolve our protection. After this, we apply solvent for the protective layer. Assuming there are microscopic holes in the top paint, the protective layer will dissolve and the top layer will go off with it.



The layer must not be obvious.

I was considering these:


Ethanol-based transparent paint (too expensive, suprisingly)
Wax (parafin) based layer (I don't know how to dissolve wax, it's crystalic so not transparent)
The "professional" solutions here in the US are often fluorinated paints. My understanding is that the graffiti literally slides off and people give up after a few tries.

Given the costs, my suggestion would probably be a thick layer of polyurethane. These are often applied to seal wood floors and can be transparent or stained. If you apply multiple layers (say 2-3 on a floor) the surface is very smooth and slick. It's hard for paint or other stains to stick.