What Is Self Etching Primer? Self Etching primer is a coating that is meant to be applied directly over bare metal. ... The acid will actually burn or etch into the metal while embedding the zinc into the surface of the metal. This ensures good adhesion and rust prevention.

When should I use self etching primer?

After you remove the rust scales from the metal on your car, you need to apply self etching primer. It's a mix of phosphoric acid and zinc. The way it works is that the acid forces the zinc into the top of the metal. It's purely a surface coating, and it doesn't stop the rust.

Can you paint directly over etch primer?

You can't paint directly over etch primer. You need a surfacer or other primer/sealer over it.