Hi, all,  Can someone explain why the nap side of leather should not
be used against metal valve plates as used in Standard or Autopiano
actions?

I use a bubbler connected to a block topped by a single Standard valve
plate to check valves for tightness and for other tests as well.  I was
recently checking out a leather skin and found that the nap side sealed
better than the grain side.  I know this will vary from skin to skin,
but the test made me wonder whether anyone has restored the secondary
valves on a Standard using the nap side against the plates, and if so,
what the results were.

Tim Gautreaux