Yellowing bathroom walls

I used white Plastidip on the exterior of my skylights to keep the sun from turning the wet bath yellow.

It prevents the problem but doesn't fix already yellowed fiberglass.

Is it plastic or fiberglass? IF its fiberglass, and aging, that's pretty much what it does as it ages. You can try refinishing it with Rustoleum Topdeck walk on grade marine paint.

If its Plastic, you can try what's called "Retrobrighting", which requires Hydrogen peroxide paste, saran wrap, UV light and some heat.

If done incorrectly, you'll get a nasty pattern on the surfaces.

Rust oleum sells spray paint specifically for plastics available at HD…I’ve found that it works well, and might try it out on some scrap plastics and also test for some flexing…

3 tons

Peroxide paste and ultraviolet light.

Paint.

First thing I would try is L.A. Totally Amazing from the Dollar Store. Walmart has it occasionally as well. Saw it in gallons at Home Depot. It works well on "some",not all, plastics that yellow.

Yes I am talking about the wet bath

If your talking about a large like a wet bath, maybe renew the gel-coating…

3 tons