I am just amazed or, for a better word, appalled at the amount of
postings concerning materials to seal leather pouches.  Let me get
to the point.  _Leather pouches are not to be sealed._  Yes, you
read it right!  The only pouches that were originally sealed were
Aeolian with thinned rubber cement which did not hold up well without
maintenance.  Aeolian also used egg whites which worked very well and
is the _only_ recommended sealer to use on rare occasions.

There are many reasons not to seal pouches.  For one, they were not
originally sealed.  Sealing a pouch changes the characteristics of
the pouch.  There are reasons why leather material is used for pouches.
Overall it's lightweight, virtually air tight and flexible.  If you
seal it with rubber cement you now have a rubber pouch because it
affects the overall properties of the pouch.  Just trying to elaborate
a little to paint a picture.

Sealing a pouch is just putting a Band-Aid on the problem and most
likely was derived from someone misdiagnosing or not understanding the
real problem.  You always have to start with the basics.  A pouch has
one job, to push the valve.  It's either working or not.  Seepage
through a pouch is not and should not cause any operational problems.

Most actions when they where designed took into account that the
leather will have a certain amount of seepage and balanced it with
the bleeds.  It's like a seesaw, balancing atmospheric pressure.
Of course, too much seepage will result in the pouch not operating
and then it needs to be _replaced_ not painted with rubber.

Sealing a pouch would be the last thing on my priority list and would
never come to that.  You have bleeds that can be adjusted, seepage
through wood, valves not seating properly, leather on valves leaking,
wrong valve travel, vacuum leaking in the system, passageways obstructed,
to just name a few.  You will ultimately find that sealing a pouch will
only yield you negative performance and hamper the repetition.

I just can't fathom someone having an action totally disassembled,
looking at the pouches and coating them with rubber instead of doing
the right thing and replacing them.  Today if you want an airtight
pouch there is "Maroon leather" available that can be purchased from
The Leather Supply House or Columbia Organ supply.  You could also use
insect-treated zephyr skin.

As time goes by I have noticed the loss of understanding on how these
pneumatically operated instruments really operate.  All of the
over-thinking and short cuts are becoming standard practice and have
concerns for the future quality of these wonderful machines.  There is
only one up side.  Because of these types of practices, it keeps me in
business.

In conclusion, don't seal pouches!  There's more harm done than good.
Couldn't cover everything.  Hopefully everyone gets the idea.

Musically,
Robert Loeffler - Roberts Musical Restorations
Deland, Florida
http://www.robertsmusicalrestorations.com/