Naval Jelly is
Phosphoric Acid, chemically changing the iron oxide (rust) to iron phosphate - available in many forms and in many products - it's more a rust
converter than a rust
remover, once the rust has been turned black you can carry on with the paint, providing you're not trying to get a mirror finish for a show machine, only other way is to mechanically abrade the piece [grind, sand, chip] down to clean steel, in some places an air chisel might work
Bill
