Depends how you are riveting. Hot or cold. If hot riveting the paint will burn. I primed and painted the spokes and rims of my traction engine wheels prior to assembly to prevent rusting. Assembly was done at a later date. The setting of rivets on the spokes where done cold. (5/16" dia rivets were set with 3 different shaped snaps, requireing a maximum press force of 15 tons). The assembled wheels then grit blasted prior to final painting.

Paul

For riveted assemblies on my traction engines such as strakes to rear wheel and spokes to wheels I spray the mating areas with grey primer before assembly. My guess would be that the joint would be sufficiently tight (all rivets closed cold) that the thickness of paint is immaterial. The rivet expands to fill the hole, so it's a pretty tight fit. Try getting one out when forming the head has gone pear-shaped!

Andrew

Back in the 60's at the aircraft factory, we painted all al alloy panels in an undercoat before riveting . For military aircraft, we painted, and then all external seams had a jointing compound (can't remember the name , it was yellow and it washed off with soap). If panels had to be "fettled", the bare surfaces were etched with a brown 'acid' called Alachrome? and washed before riveting to the adjoining structure.