I don't know if I remember this right. But after using Naval Jelly the
chemical needs to be washed off with water before painting. Anyway when
washing bare metal (iron) with water a coat of rust will develop from the
interaction of metal and water. This reaction is unnoticeable to the
naked eye. After painting areas that was treated rust developed after a
few years. That is one of the reasons cars of before always rusted on
body worked areas.  Products such as osphos and other metal protectant
products became more popular. They do not involve water and the chemical
reacts with the rust that cannot be seen or cleaned to treat the metal
before painting. Everyone feel free to trash me if I am wrong. Aloha, Ed