Ospho, aka phosphoric acid, is used by my body shop after wire brushing and sanding and prior to applying the etching primer.
We used Ospho on the ships in great quantities. Phosphoric acid converts iron oxide (rust)to iron phosphate, which is inert or stable. You can find Ospho at most hardware or marine supply stores. For more details about this product take a look at
Ospho I hope this is not considered advertising as I would hate for the zookeeper to lock me up
