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MMD > Archives > June 2016 > 2016.06.06 > 04Prev  Next


Sealant for Leaking Pouches
By D. L. Bullock

[ Michael Hurley wrote in 160603 MMDigest --

> I am restoring a player and am having an issue with pouches not
> holding air.

I take it that these are original pouches that you say are leaky.
First of all they are 90 years old or more.  Leather cannot last that
long and stay usable for another 20 years.  If you are restoring
something that is not going to last at least 10-20 years before you
or someone else must "restore" it again, then it's a waste.

Second, the problem you have is not leaky leather in 90-year-old
pouches (and this can be a problem even if the pouches are new) -- the
_real_ problem you will find is the shellac in the channels is leaking
everywhere.

To test my theory tape up all the holes in the pouch board going to
the pouches.  Now also tape up the bleeds if there are any (secondary
pouches don't have bleeds).  Now open several of the holes across the
board perhaps 3 or 4 of them, spread out from end to end of the board.
Take a tube and blow into that pouch hole gently but firmly -- blow for
10 seconds.  Watch the pouch rise.  Then watch the pouches to each side
rise slower than the first one!

I had one recently that was "restored" by 6 or 7 rebuilders before me
and all the new pouches were in place and doing their best but nothing
worked right.  I did this test and I found as many as 5 additional
pouches rose besides the one I was blowing into.

The solution to your problem is not a pouch sealer but removal of
pouches and pour or squirt shellac through the channels and pouch wells
in that pouch board.  I use a squeeze bottle to do this, then use a
brush to smooth out the pouch well itself, then drain it all for an
hour.

Blow through all the channels to remove extra shellac and let it dry
overnight.  OF course clean all the shellac off all surfaces that you
need to glue to or put a gasket against.  You must also remove, clean
and replace bleeds if they are there.

_If_ you need to sand the pouch surface of the board, do so and remove
all shellac for when you glue down the pouches.  Replace pouches and
use quality pouch leather which is tan or maroon and not that gray
stuff that is so porous.  I get mine from Organ Supply Industries (OSI);
perhaps you have another supplier.

While your solution to the pouches using sealer alone was once the thing
to do, at this age all shellac-sealed channels are very, very leaky and
it can make the difference between a leaky slow responding player and
one that plays like a new one.

Doug L. Bullock
www.facebook.com/doug.l.bullock


(Message sent Mon 6 Jun 2016, 16:09:45 GMT, from time zone GMT-0500.)

Key Words in Subject:  Leaking, Pouches, Sealant

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