Thought rust converter spray was snake oil until a 1998 Tacoma proved me wrong
I always figured those spray-on rust converters were just purple water in a can, so I turned down a guy in Bakersfield who wanted me to try it on his beater. He left the truck with me for two weeks and when he picked it up the frame spots were black and solid instead of orange. I poked at them with a screwdriver and they didn't budge. Has anyone else had luck with this stuff on real rot, or does it only work on light surface rust?
Spray converters get a bad rap because most guys slap them on flaky scale rust and call it done, which never works. That black coating you saw is just iron tannate, and it only holds up if you knock off the loose stuff and let the product soak into solid metal. Real rot with deep pitting will still come back from behind, so keep an eye on those frame spots in a year or two.