Hi All,  Sometimes I just don't have enough willpower not make a post.
I started to just email John Tuttle but found that I typed so much
I thought I would just post it.  I was amused in John's results when
he mentioned the sealers that worked well also made the pouch stiffer.

The more you test, the more the outcome will match exactly what I have
posted many times in the past.

I've done soooo many experiments and you will ultimately have the same
results if tests are done to match the operating mechanics of a typical
player piano.  Personally, I think you're trying to fix a problem that's
not there or is rarely the real issue.

First, you need to test a pouch to see how much leakage is acceptable
before it interferes with its performance or reiteration.  You will find
that 98% of the systems out there will allow for more leakage than you
would think.  Leakage was originally thought into the process/design
when they built these systems, and now better leathers are available.

This is a typical mistake that people make.  Just because you have one
or two player systems out of 100 that need the pouch to be completely
sealed to operate correctly does not mean the rule should be the same
for all the rest.  Personally, after all the testing I have done,
I conclude that the few systems that need the pouch to be 100% sealed
were not designed or engineered properly.  And even if you thought the
world of that particular system you can't or shouldn't try to change
or restore other systems in the same way.

In a particular system where a 100% sealed pouch is needed, it's
needed because of other factors like signal tube size, tube lengths,
tracker bar hole size, bleed etc.  If all of these factors aren't
thought through correctly you will have issues.

Keeping all of this in mind, one would assume that in the cases that
you have a system that needs the pouch to be 100% air tight, that at
the beginning of manufacturing they did not seal the pouch as no one
else did.  Then when testing the system they found out that there were
a couple of minor miss-calculations that were made, like signal loss
due to small tracker bar holes, tube lengths, etc., like I mentioned
above, and the easiest fix was to seal the pouches to get the system
up and running.  Maybe for some reason they couldn't install larger
tubing or increase the hole size on the tracker bar or larger channels
in the system, etc.

At the end of the day the system might work great, but is it
mechanically balanced?  Well, compared to all the other systems that
you can have, a considerable amount of bleed through the pouch without
effecting the performance I would not use that particular system as an
example for all.

Like I have mentioned in the past, the pouch is either bad or good.
Just replace it and if you still have issues 99% of the time the
problem is not the pouch; it's valve travel, blocked bleeds, etc.

Another oversight that I have seen in testing certain valves for
reiteration is the length of the signal tube that comes from the
tracker bar.  You have to allow for the diameter in some cases and the
length of the signal tube because it effects the bleed and reiteration.

When I conducted tests, I tested the activation of the valve using
the longest length of tubing run that's used on that particular system
in activating the valve to ensure valve performance and get a more
realistic outcome.  This showed more the effects of a sealed pouch and
why the flexibility is important.

This is why in some cases in German orchestrions that have long runs
they use zephyr skin because it reacts faster to a minimal signal.  Not
that it's 100% air tight -- some zephyr that I encounter isn't air
tight but that's not the most important characteristic of a pouch.
It's mainly the pouches flexibility.

And I know as soon as I mention Zephyr, all the naysayers out there
will say "Well, he uses zephyr on everything."  Wrong!  Like I have
been trying to explain, there is a reason that certain materials were
used depending on the circumstances that I have mentioned.

For example, in many large orchestrions that have been restored, using
regular pouch leather instead of the original zephyr always compromises
the performance.  I have been saying this over and over: when you seal
a leather pouch with some foreign substance you're taking away its main
function.  Just think back to all of the ridiculous recommendations
that have been posted over the years, from using whale blubber to motor
cycle oil.  Totally ludicrous!

The same thing goes for people using the newer pneumatic cloth that's
installed with PVC-E glue.  This is another subject that I could write
a whole book about.  But without going into detail it's very similar to
the "sealing pouch" issue; you're creating or changing a material that
creates more negative harm to mechanical instruments than positive for
no reason.

Yes, the original rubberized pneumatic cloth would get hard when aged
and sometimes gets holes in the folds but the modern day rubber does
not have that issue of drying out.  I have seen time and time again
these new materials to look in perfect shape but the rubber membrane
breaks down and starts leaking.  Also the material is very weak, thin
and stretchy in some cases that causes a very sloppy pneumatic.

Not to mention I do not use and do not recommend using PVC-E or any
plastic glue in contact with wood in a restoration.  Some claim it's
only used on the pneumatics because they normally get trashed and new
boards are made, but from what I have seen, when someone uses plastic
glue on the pneumatics it is always is used throughout to entire
machine.  Valves, gaskets, etc.  A disaster!

In conclusion, I wouldn't keep wasting time trying to find out what to
seal leather pouches with because then you really don't have a leather
pouch anymore by doing this, like someone recently mentioned.  Maybe
trying to find a new material all together that will be flexible and
air tight.  But still a waste of time being that it would take years to
test the "test of time" effects when just using the modern day leathers
available will last 60 years when used correctly.

The same goes for rubber pneumatic cloth.  I would never recommend
using anything that requires plastic glue.  The only use in my shop for
PVC-E glue is leather on felt, felt/leather to metal or in some cases
zephyr pouches being that the excess hide glue can cut into the pouch
in certain situations.

A little respect for these mechanical music machines goes a long ways!

Musically,

Robert Loeffler - Roberts Musical Restorations
Deland, Florida