Pre-treatment of mating surfaces before assembly

[permagray]

When assembling skin pieces that might overlap, does one put some sort of sealant on the joining surfaces before riveting?

[PhilipRueker]

The factory suggests to prime mating surfaces (aka the touching parts).

That being said, the Aluminum used is 6061-T6, which is already fairly corrosion resistant, so some builders don't do any priming.

If you want some more thoughts about priming, check out this thread.