Yes, you can clean wooden piano action parts in a blast cabinet with
the right grade of glass beads or walnut shells.  You can also reduce a
fine piano action to driftwood in a few seconds if you're not careful.

If you're going to try this, turn the pressure way down, to 15 or 20
psi.  Hold the blast nozzle 20" away from the part.  Aim it at one
small area for 3 seconds.  Take the part out and look at what you've
done.

If you do it right, the wooden parts will look and feel as smooth
as brand new.  The edges will still be factory sharp.  If you're too
aggressive, you'll round the edges and the wood will feel rough.  If
the humidity is too high, the beads will clump and you'll be tempted
to turn up the pressure.  _DON'T_.

I once installed a new set of hammers in a fine Mason & Hamlin grand,
in which a novice had used walnut shells and turned the beautiful
original action parts into a rough, ugly driftwood mess.  I'd rather
see a piano with dark-colored parts than one that looks like it laid
around the beach for a month, after being blasted too aggressively.

One other thing to note: we only use this method on action parts in
which _all_ bushings and other felts will be replaced.  I hate to see
the little piles of glass beads and red cloth particles laying under
the action parts a year later, after the bushing cloth starts to erode.
Some technicians advocate covering all the bushings with masking tape.
I've seen masking tape adhesive migrate under other circumstances, so
it concerns me that this method might cause the bushings to get gooey.

Art Reblitz
Reblitz Restorations Inc.