I am happy that Bob Hunt has not had trouble with his fleece backed
bellows cloth.  I have been gluing on bellows cloth since I was a high
schooler.  I have been doing this for over thirty years (I won't say
how many over 30!).  I was one of the first to suggest we iron the
bellows cloth onto our wood and many thought I was crazy then.

I have searched the world over to get the best quality glues after I
realized that the hot glue that we got in the store was trash.  I use
the best out there.  I still do not buy it from the normal suppliers
because they are not high enough quality.

I have used all varieties of cloth suppliers and settled on the
Australian cloth when it proved to be the most dependable.  The fleece
backed cloth, which has now cost me about $30K in lessons learned, was
crap.  I do not need a tutorial on gluing bellows cloth.  I have used
fleece backed cloth since the early days of my restorations.

I am happy that Bob's cloth is not leaking; perhaps he got a good batch
-- I used to.  But the problem with the Australian cloth is not the
glue job.  Both I and Mike Madeira tried extra glue and ironing as well
as several techniques and glues you have not used.  We both had the
same problem.

I suggest that you take two extra spring loaded reservoirs, the ones
that you remove from a Standard to put in an electric suction box, and
cover one with your cloth.  Send me your measurements and I will send
you a piece of my cloth.  You cover the other reservoir with my cloth.

Clamp both of them closed and tape up all screw holes and air holes.
Take off both clamps and time their opening.  I suspect that even though
your cloth may not be the cloth I had trouble with, my new cloth will
last longer.  I use this very reservoir to test my leather, and mine
went from 8 minutes to way over 30 minutes when I changed cloth on it.

I just finished rebuilding a Duo-Art pump, with my new cloth and my new
leather, that was previously rebuilt by one of the finest rebuilders I
have ever met.  The piano playing was lackluster before.  Today I will
put the newly restored pump into the piano and I will let you know what
it is doing then.

I just reassembled the pump yesterday and, upon taping up the two ports,
I tried turning the large wheel by hand -- I can only get it to turn
about a quarter of a turn or less before I cannot turn it any farther.
With both hands I can get it to barely turn some more.  I opened one
port and put on my suction gauge and did it again.  The needle maxed
out on that quarter turn and when I let go of the wheel, the needle
slowly went back to zero.  This pump has no reservoir attached.  Now
that's airtight!

I still have some of that cloth left.

D.L. Bullock
http://www.pianoworld.us/