Based on suggestions from Doug Weiler, I stopped by Napa and bought 2 spray cans of self-etching primer. It took 1 can (cost: just over $4) to prime the 8 wing ribs that I had replaced in the left wing. I did that on Saturday in the garage -- and the garage still stank of primer on Sunday. However, the primer seemed to cover well and felt solid.

The ribs have been riveted to the reinforcing brackets and are ready to rivet to the main and rear spar, if only I can find my bucking bars.

I think I'm supposed to pop rivet the ribs to the main spar, as you can't get to both sides of it. That just seems weird, too.