Hello -- My previous inquiry about possibly sealing sturdy but porous
bellows cloth garnered many fine ideas from MMD'ers, so I thought that
I'd relate my experience.  I chose to go with Craig Smith's suggestion
about using Pliobond as a sealer (see his entry for May 3, 2010).

I found Pliobond 30 offered by McMaster-Carr, recommended for working
with porous materials.  By (my) mistake I put on a first coat of
heavier than recommended consistency -- about two-thirds Pliobond,
one-third acetone.  My second coat followed Craig's suggested 50-50
ratio.  After a thorough drying, I powdered the cloth well and vacuumed
up the residue.  I also replaced two questionable valve flaps and
shellacked around through-bolts and screw holes.

The results are most acceptable.  Although my other Classic with its
factory-installed bellows cloth of a different manufacture pumps a bit
more easily, this one, which couldn't previously wheeze,  works
exceedingly well.

A big thank you to all who helped!

Tom Sendall