Lawn mower paint and cleaning?

The pressure washer will work. Rust-o-leum will work to paint it also. It'll last at least a year or two. I would paint it in the fall after you are done mowing. It'll give it all winter to dry . The original finish is baked on and is harder than any paint you can do yourself. The gr is the equivalent to a sandblaster underneath the deck, it beats the paint off. Dougl' idea for undercoating is not good. It'll be either too soft that the clippings will get imbeded into it, or so hard & brittle that it'll start falling off in chunks.