de Havilland Vampire and Venom surface finishes?

[BarnOwlLover]

I'm asking this because I decided to look and see how the Vampire and Venom (which are mostly metal aside from the front fuselage) were riveted together and how surface treatments may've reduced drag. I found that the Vampire and Venom (and probably most aircraft of their period) were exceptionally clean. I kind of had to strain to see the rivet marks on the metal components.

Was there some special surface finish applied over the airframe to smooth the rivets out, or was the riveting that good, or is it just paint?

 

[Barf]

The Vampires are flush riveted to a reasonably smooth finish. Additionally, the wings and horizontal stabiliser are filled, profiled and sanded smooth before top coating. This aids the laminar flow wing, the same as P-51 Mustangs.