Originally Posted by
Kontact
4130 gets surface rust and then largely stops. It doesn't rust like a *****, because it doesn't form the kind of blooming rust that deeply pits other steel alloys.
Huh, good to know. I knew there were architectural exterior steels that rusted to a certain point and then stopped, at least according to dad; Commercial buildings like that were very much in vogue in the '70s, zero exterior maintenance.
My folder frame and fork is 4130, probably not terribly thick, so the few small spots of rust it had when I got it, I Osphoed and touched up with reasonably matching fingernail polish.