"etching primer" doesn't neutralize any rust, just makes better 'tooth' for the next layer, the rust will come thru eventually - a rust converter will work, and some can be primers - an ecapsulator can also work, especially if they're at least partially a converter, but I prefer to use the phosphoric acid as a 'converter' to eliminate the iron oxide and the oxygen that will be entrained in it, leaving iron phosphate to protect for a short while - begin coating as soon as dry, heat guns help
Bill
