I have seen serveral posts about people using self etching primer. It seems to be a popular way to go, but what exactly is self etching primer? What advantage does it have over an ordinary primer? Sorry for the easy ?, but I am not a paint guy!

-Shark Mann

 

An etching primer is for superior adhesion to metal than an ordinary primer.
It would be the first layer laid on. Not needed or desired to use on fiberglass.

In any case, epoxy primer is superior to a self etch and is also excellent for fiberglass.

 

Thanks for clearing that up!

 

Self-etching primers are used on bare-metal surfaces only, where you want the ultimate in adhesion and corrosion protection. They are very low in solids with next to zero filling qualities. They usually can be followed with a primer but you need to follow the manufacturers topcoat guidelines, and some can't be top-coated directly with paint. Etching primers aid in adhesion and corrosion protection under other undercoats such as 2k urethane or epoxy primers. Very important to check the recoat window time and compatibility with the primer surfacer you are using.
One example is DuPont 22860S. This wash primer maintains excellent corrosion resistance and direct-to-metal adhesion for spot, panel. and overall repairs.

Some advantages are:

Contains high levels of zinc for corrosion resistance

Eliminates the need for acid washing prior to priming which saves time. Etching primer contains acid which cleans and bites into the surface for improved adhesion. Simply use wax and grease remover prior to applying etch primer. If you were to use epoxy primer, you would need to wash the surface with a compatible acid first, rinse, and dry before applying the epoxy.

Etch primer is non sanding

In fact, many dental coatings use a self etching primer with contains acid.

 

I agree 100% with Roger. Self etching primer is not needed on fiberglass. Epoxy then a good 2k or polyester primer is the way to go.