Hello,  It is interesting to hear restorers who are adamant about using
original materials and then hear of problems caused by using the same.

The problem is that original materials are not available today.  What
we have is a range of imitations, from good to bad.  Unless materials
available today are tested with accelerated aging methods that truly
simulate the passage of time in today's environment, no one will know
which will fare better: modern imitations or substitutes.

Rubber formulation has always been a problem, with only the very best
materials likely to last a reasonable time.  Even the best does not
survive under certain circumstances.  Who has not rebuilt a player
stack to find half of the pneumatics in good condition and the rest
dried out and useless?  This is not a matter of the manufacturer having
used good or bad materials but variation from batch to batch.

Leather is even more of a problem today as the tanning methods and
hides of yesteryear are simply not available.  Beautiful looking
leather is available and we can only hope that it will last as well as
the original material.  Many anecdotes suggest that this will not be
the case.

Fortunately, hide glue is still available and is the best choice for
most player work as it is fully reversible but not necessarily in the
near future.  Removing stack pneumatics that were glued on 70 years ago
is usually not a problem, but what about ones that were glued 5 years
ago, especially when glued to previously damaged surfaces?  This is
likely to be necessary when today's "best" pneumatic cloth fails.

Randolph's suggestion of GE silicone adhesive I sounds promising and
time tested.  My only hesitation is that silicone is addictive.
Nothing else will stick to a surface that has silicone absorbed into
it.  However, it sounds like the advantages might be worth the risk,
in this case.

My solution, in cases where I thought that rebuilding might be
necessary fairly soon, was to use screws and gaskets but this involves
a lot of extra work.  I rebuilt my Welte Vorsetzer this way and will
probably be glad that I did, as the "best quality available" cotton
pneumatic cloth is already showing pin holes at the corners after very
little use.  Substitute materials were used for other parts and I am
pretty confident that they will outlast the cotton cloth.

I think that the best that can be done is to use caution and research
as much as possible to find the best materials available today and to
use them in a nondestructive manner, with regard for future replacement.
If modern substitutes can be used without destroying the original parts
with glues that can not be removed, there is no more damage done than
using an original imitation that will last only a short time.
Unfortunately there is not enough demand that ideal materials can be
specified and manufactured at reasonable cost today.

It would be ideal to have a database available to MMD subscribers and
others of materials that are available today, both original, imitations
and substitutes, including sources and information about longevity when
available.  This would be of great to any restorer facing the decision
of what materials to use.

Best regards,
Spencer Chase