Hi All,  I've been running a lot of bubble jar tests in the effort
to find a valve facing material for the intake facing in the Standard
double valve system.  And, while I believe I've found what I was
looking for, I've also come up with one nagging question that I can't
answer.

What I can't figure out is why any manufacturer would use leather that
isn't perfectly flat and smooth regardless of the size or type of valve
seat?

Any leather that has a skin texture, of any sort, has small passages
along the textured surface through which air can pass.  And even if
you apply pressure to the facing, air still gets through.  I've also
found that any leather that is 'fuzzy' leaks even more than leather
with a fine texture.

I know that, for perhaps decades, PPCo produced numerous synthetic
valve facings in the effort to reduce valve leakage to a minimum.
And, as many of us found out, there were some unintended consequences.

Still, if you have a flat smooth valve plate or valve seat, wouldn't
it make more sense to have a flat, smooth valve facing?  What comes to
my mind is the valves in a car engine.  If the valve seat doesn't mate
the valve perfectly, the performance suffers.

Musically,
John A Tuttle
Player-Care
Brick, New Jersey, USA