I replaced my cab corner today and have ground the welds pretty smooth. It needs some duraglas so should I prime the raw metal before the glass or go right on the raw steel? which primer would be best? I have rattle cans of self etching, grey sandable and red rust primer. I don't have access to a spraygun and the epoxy primer at this time.
SPI epoxy primer ships out of GA, If you ordered it when you made this post, you would have paint drying by now.
Anything out of a spray can is not going to seal out moisture as well as epoxy, and in some cases the spray can primers are not compatible with the solvents in Automotive paints. When quality paints and topcoats are running about 100 a quart on up (generally speaking), I'm not going to trust a $5 spray can to provide an adequate substrate for the money and effort involved to get to that point. ......Unless you're after a spray can finish, then by all means carry on. For a long term project (it won't be done in three days like most jobs in a body shop) epoxy will give the best protection from moisture intrusion to the steel. A single component spray can primer does not seal out moisture. No spray gun? Mix up the amount needed and either brush or roll it on. You'll be block sanding later so the imperfections won't be the end of the world.. But it will hands down be a better foundation for whatever you decide as a topcoat.
