First, do check for corrosion because that's the only "powder"
I know of that could be under a rivet.

AND if that's what it is, seriously consider replacing all the rivets.
Corrosion under rivets means things are working loose.
It is not an indication of a structurally sound wing.


As for filling dimples?
I have been trying out blue bondo as an alternative.

Just doing rivets, usa a small stiff squeegee to fill,
then flush each rivet.

Wipe off any streaks before they set hard. Don't leave them
to sand off later!

Repeat as necessary, since is is still a polyester based resin.

BTW, the blue stuff has a creamier consistency and seems more
fragile in the green state than old red bondo. Finer texture.
But once hardened, it has a smoother surface and sands out slick.

It also takes microballoons, cabosyl, flock, etc. well (BEFORE
catalyzed!).

I use a little bit of this stuff here and there, usually to fair
intersections.

I do NOT lay on thick layers to build up a smooth surface.

Layers of any filler add weight.


Richard



BD5ER wrote:

That "powder" sounds remarkably like corrosion, so it might behhove you
to drill out a couple of the rivets with the most powder and see what
lies beneath.


Once you have eliminated corrosion as the source of the powder and repaired as
needed, try some Superfil. I've not heard from anyone that was dissatisfied
(knowing this group that may change). I'd stay away from polyester based
filler. It tends to swell in the wet and crack in the cold.