Last week I did a pre-winter check of the exterior body surfaces on my 1990
syncro camper to look for places where the body is rusting and to touch up
minor scratches.

I have the factory two part clear coat/base coat paint combination and
working with this paint raised some issues.

I found that I could spray the basecoat on with a $10 Bager airbrush that
attaches to the spare tire (for air pressure) that I bought from JC Whitney.
An expert at the beach house urged me to sand the basecoat with 1500 grit
sandpaper before spraying on the clearcoat but when I looked in the official
VW factory paint finishing guide it seems to say not to sand the basecoat at
all, but spray the clearcoat finish on after 15 mins. Then, if desired, one
could sand the clearcoat after a day or so.

Who is right?

The Bager airbrush didn't match the beauty of the factory paint finish but
this was OK as I was only painting under the bumpers and on the far lower
body panels. I wonder if anybody on the list has an opinion as to how I
should do it next time when I have to spray some of the body panels that
show.