This Q should be in “Rust Prevention…” catagory but looks like more activity here.
I think I made a big mistake when I undertook the project of doing a “Bed Off” restoration of my ’96 F-150 to stop what I thought was frame rust. The entire frame has a coating of rust so after removing bed and other access prep I started wire wheeling with a angle grinder only to find that everywhere I’m stripping the top layer of rust off with the wire wheel there’s a good coating of some kind of softish black frame coating or something underneath. The wheel won’t take it off but just sorta melts/smears it. No way would I have thought that this stuff was present when I looked at the frame. For all intents it really looked like the frame was rusting. My goal was only to stop rust and I’m not doing anything other than that. At this point I’m hoping to get some advice. Should I STOP where I’m at? i.e. the topcoat of rust is NOT an issue?