If you test your pouch leather with a bubble jar you will find that
all pouch leather will leak to a certain degree, and, depending on
the degree of leakage, which will most certainly increase with age,
it will require sealing.

There are many methods used in the restoration shops.  My method is
detailed at  http://www.pebworths.com/UsingRTV/  This is my method.
Others have their favorite method.  I have been using this method
since 1980, and have been very satisfied with it.

Al Pebworth
http://www.pebworths.com/