silly engine painting question

[mattyo]

Originally Posted by roscoenr

The primer usually has an acid in it that helps it bond, or etch, to the metal surface. Then the paint will have a good surface to stick to.

Agreed, but I thought a sand blasted surface would already be a good bonding surface. But if the primer etches itself into the surface then this implies something happening on the molecular scale to create a good bond verses the sand blasting which is more on the macroscopic level. Fair enough, time to buy some primer. Thanks for your suggestions and quality information!

[mattyo]

Originally Posted by atdawnweride

As mentioned, the primer acts as a bonding agent. I don't have the scientific evidence or explanations in front of me, but I do know from experience that paint on a primered surface will look better and last longer than on an unprimed surface.

I learned a long time ago that skipping steps and cutting corners during paint prep only costs more time and money when you have to repeat the process much sooner than you should have to.

Agreed, I don't want to go through all this work to have it peel off in a couple months. Just wanted to make sure the physics/chemistry behind the primer was lining up.

[mattyo]

On a side note: for these high temp paints and primers, is it best to heat treat after each coat of primer/paint or can you prime/paint the whole deal and then do one heat treatment?