Body work

HI guys it's me again! Thank you for the input on what to look for after my car was smacked pretty good ( Sorry about posting the pics, I had NO clue). My question now is I am almost ready for paint, but while it was in the shop today (wheel cylinders, I am in appraisal school, no time to fix them myself) the co owner of the shop offered to paint her for me. I told him I was gonna wait because I have rust bubbling through my quaterpanels and it seemed pretty silly to paint her to destroy her again. He mentioned that he could take care of that for me with some kind of acid he said would remove the rust, and fill it with lead?!?! I kinna missed that part. I told him NO BONDO, he said he wouldn't. I in no way commited to this since I have never heard of this acid "Cure". Anyone else heard of it? Whats your take on it? Thanks, Bill