An excellent source for leather is Columbia Organ Leathers, in
Columbia, Pennsylvania.  They have always been efficient and a reliable
source for quality leather.

I use their cowhide (CCL-pak) for Duo-Art cross valves.  Glued on with
hot hide and cooled in a lightweight press (mine does eight valves
before I lift the press), the result is as tight as what Aeolian
produced.  It looks like their work, doesn't take a cross pattern,
doesn't gather dust and dirt like "fluffy" leathers.

If you follow the old rule of rebuilding cross valves upside down, your
cross-valve stack should be tight as tight can be.  The stack I built
for my Steinway B thirty years ago still runs evenly, like brand new.

But don't take my word for it.  We've all read advice that seems to
have come from outer space.  Ask them for a sample and try their
leather for yourself.  The company's website is here:

    http://www.columbiaorgan.com/col/ 

Bruce Grimes