Of course priming begins by using Maroon Scotchbrite to lightly scuff, then by degreasing with Acetone.
The spars are quite long, so I ended up fitting them diagonally across my spray booth. The picture shows the smaller parts with the acid etch applied, and the spars have had the white acrylic sprayed on over the top of the acid etch.
All finished, so I left it for a few days while I was away at work, to allow the paint to harden before riveting.
Rib Tab Holes
When final drilling the rear spar to the rib tabs, the ribs had already been primed. So I decided for completeness to spot prime the holes. It only took a few minutes after raiding the bathroom for a cotton bud!