Robert,

I think the paint trick is a good idea. After my final buffing I can
see that I missed some areas with the finer grades of sandpaper -
leaving some scratches visible in the right lighting when viewed from a
low angle. You can't see these until buffing is almost complete. Using
weak paint before each grade of sandpaper would avoid this problem.
Will try it next time!

Stuart


Robert Ehrlich wrote:
This is done almost routinely in my club. The club has a permanent
employee
who manages the flights during the soaring season and do the
maintenance
work during winter. As part of this job he repairs the various
scratches
on bellies or wing following outlandings in the way you describe and
if
times remaining permits (we have 20 "plastic" gliders) he completely
refinishes the glider with the most cracked gelcoat (the last time
this happened
was 2 years ago). Under his supervision a private owner also
completely refinished
the fuselage of his Nimbus3 last winter.

When I watched this work, I saw they used a trick that you didn't
mention.
Before each wet sanding pass, they paint the surface to sand with red
paint
very highly diluted with aceton. This helps to stop the sanding
where/when
the paint is gone by sanding.