47-55.1 Removing old paint and rust

[Stepside Jim]

Great answers.

Bonding, etch bonding, chemical bond, mechanical bond.
Etch, an acid effect, creating microscopic hooks into the metal for grip/bond.

Chemical bond, where two liquids both not fully cured, come together/bond by their solvents melting together becoming as one.

Mechanical bond, scratched, or microscopic pits left behind from media blasting. The adhesive properties of the Epoxy primer and the primer gripping the scratches and pits provides the bond.

Since we're focused on Epoxy primer, and notice both of you agree to let Epoxy cure fully before the next step yet, some Epoxy primer companies say you can spray over it as early as an hour, usually recommended 24 to 48 hours but before 5 days. During this first 48 hours, wouldn't this be a great time to use the Chemical bond method then prime with a high build primer or paint and skip the wait and sand then top coat?

Consider your answer since it has become extremely common to use Epoxy primer as a final sealer before final painting, using only the chemical bond between the Epoxy/sealer to the paint finish.

By waiting for it to fully cure are we not losing the chance for the chemical bond between high build primer and Epoxy primer.

Being a 2K product, does Epoxy primer not continue to cure when top coated with in the first 5 days?

When I look at the pictures provided in the original post, I see rust pits, pits that sand paper and wire brushing will not reach the bottom of the pit and leave the loose rusty specs behind in the bottom of the pit, blasting will get to the bottom of the pit and find clean metal.

Either way of blasting, sanding, or wire brushing, what ever primer you spray over the rusted pit you will not be able to sand scratch the depth of the pit once the primer is fully cured. Every pit will not provide bond since chemical bond is past tense and sand paper will not scratch the inner part of the pit. If you do try to force the sand paper into the pit you'll expose the metal surrounding the pit causing you to reapply Epoxy primer to coat the metal again.

Once again, a perfect time for the chemical bond, first couple days of Epoxy primer, to apply high build primer to settle into the pitted area and hold by chemical bonding or perhaps body filler over/forced into the pitted areas?

I'm not sure about the application of body filler in the first couple days using the chemical bond theory with body filler without sanding first, I cant find spec sheets on this procedure.