Ref. Pouches: To seal or not to seal... [Dave Krall]

Dave,  If you are using either extra thin "Aeolian/Morton" or "Tan
Pneumatic" pouch leather from Columbia Organ Leathers, you definitely
have to seal it. You also have to be very selective and check the
skin over. I have a light box I use for this purpose.

In last order I received from Columbia Organ Leathers of extra-thin
pouch leather, light shown through _all_ of the hair follicles. There
is no way to seal that kind of leakage and still have flexibility.

Usually if you do your punching within at least 6" of the edge of the
skin, the material will be more air-tight. My alternative was to use
Zephyr skin, but the last few skins I ordered from Erie Street Leather,
were not only riddled with pinholes but were kind of rotten from
sitting on the shelf, I guess.

I have some Zephyr skin and other leather samples coming from Herzog
in Germany: https://www.herzogleather.com/en/organ-building-leather/ 

Brian Thornton - Short Mountain Music Works
Woodbury, Tennessee
http://www.shortmountainmusic.com/