surface rust and amatan(sic)

I have stripped and whizzed all the paint from my bus. this has taken time over 3 month period. all bare metal was treated with a rust convertor amatan I think its called.
The areas done first esp the roof now have light surface rust which I thought would not occur due to the rust treatment.
What I want to know is if i retreat it and undercoat / prime it to what level of tolerance i do need to remove the light surface rust? is it a case of none? or sanded then treated is OK? Mitchell

Emer- Tan should be painted within 48 hours of treatment, did you do this?

Cheers, Greg

yes immediately. I am close to the sea so I am guessing that its salt spray setteling on the roof. I think Ill re do completely back to bare and re treat and paint asap.m