In  the digest  of 96.01.03 Les Smith mentions the use  of rubber
cement to seal zephir skin or tan pouch leather as an alternative
to changing bleed size in primary valves.  I  have heard of  this
but have hesitated to  try  it because of uncertainty as  to  the
effect  of  rubber  cement  on  the  pouch  over  time.   Another
alternative recommended by some  is sealing the pouch with tallow
or similar animal fat.  I have the same hesitation here but to  a
lesser degree, animal  fat  not  being  an unnatural substance to
leather.  What  do  the experts here  say  about either of  these
methods?