Hello all from the frozen northern Midwest!  Does anyone have a tested
solution to vacuum loss due to wood shrinkage other than humidity
control?  I have been plagued with this problem on my Western Electric
Mascot coin piano for the last 45 years.  Our house is old, and despite
improvements such as doors, windows, and insulation I can't keep enough
humidity during these below zero months to keep it playing - even with
a furnace humidifier and supplemental free standing unit.

I'm guessing that the vacuum leaks occur when wood in the stack
shrinks.  Can anyone confirm exactly where?  A few years ago I rebuilt
the stack, recovered all pneumatics, all new pouches, new valve
facings, quality packing leather for gaskets, etc., with materials
from Durrell Armstrong.  I still have the problem.  The pouch leather
was not sealed, but I don't believe there would be enough flow through
the pouches to contribute to the problem.

Has anyone tried using some sort of elastic material for gaskets such
that it would expand when the wood shrinks and maintain a good seal?
Or is it not leakage through the gaskets but changes in valve clearance
due to dimensional changes in the stack?  Will appreciate hearing the
experience of others to solve in spite of low humidity.

David Schroeder