Rust spot treatment (car)

[R D S]

I've a couple of rust spots, presumably from stone chips, that i'd like to treat and touch up.

Recommendations for product/technique would be appreciated.

[Animal]

Acid. Apply until rust gone, wash off, dry, prime & paint. HCl is super fast, almost instant, but the metal rusts before it's dried off by itself, you've gotta move without delay. Citric is superslow. Phosphoric leaves a semistable black coating. While better than nothing, when you paint you should remove it, it's only semistable.

[ajh]

That's interesting, I tend to use phosphoric acid after electrolytic derusting and paint over that.I thought that's why car body shells had a phosphate bath.

[newshound]

See also "etch primer", ones for steel contain phosphoric acid.