Help with deep rust on a vintage smart skillet

[mix and max]

I am wrapping up the restoration of a vintage Smart number 8 skillet after using an electrolysis tank and a vinegar scrub. The cooking surface cleaned up well but the bottom still has some spotting now that the carbon is gone. I am wondering if this is actual deep rust or just staining. I am not sure if I should do another vinegar bath to try and smooth it out or if that is a waste of time. It is helpful to inspect for pitting often so you do not eat away too much good iron. Let me know if I should keep scrubbing or if I should just season it as is. Thanks!

 

[SweetAndSpicy]

oh no, you should stop the vinegar treatment and season the skillet. the spots on the bottom are likely superficial iron staining or residual carbon, which is harmless, not deep rust or pitting.
pitting is permanent erosion of the metal and cannot be scrubbed away, continued acid soaks risk damaging the good iron, especially on the cleaner cooking surface

 

[redDragonfly]

@mix and max those spots on the bottom are probably just harmless traces of iron oxides from the electrolysis or a bit of carbon build up, not the kind of deep rust that spells trouble. you can season it as is