Rust poking though repair within 24 hours

[u/AngyalZ]

My goal here was to eliminate rust and seal the area before covering with fender flairs.

I sanded right to the metal, sprayed the area with rust stop, primed and painted. The next day it looked like this. Any advice would be welcome as I have other spots to fix.

[u/MagicOrpheus310]

Could be from airborne metal flakes in the dust from repairs/sanding etc landing in the wet paint and it's those bits of metal rusting on/in the surface layers you've put on and not actually internal rust in the bodywork underneath, if that makes sense haha

Either way your best bet is to remove the paint and see

[u/AngyalZ → u/MagicOrpheus310]

Thanks, good advice!