Several days ago I posted an article announcing my current project to
rebuild the stack on my Mason & Hamlin RBB Ampico A.  I did not fully
explain that this piano has been my test bed for experimentation.
Several modifications to the Ampico have been made, none that cannot
be reversed.

I devised a scheme of fitting a B drawer to an A piano without making
any changes to the piano.  All modifications are made to the newly
installed B drawer.  Next, I equipped the piano with the crash valve
or super amplifier system found only on concert grand pianos.  This
modification is a compromise since those systems require two pump
motors, but I retained the original single motor set up.  I'll write
more about that in another posting.

And finally, I changed all the valves to sponge.  That means the
secondary valves have a solid piece of foam sponge rubber instead
of the traditional wood disk faced on both side with leather.
Additionally, the primary outside valves were also changed to sponge
rubber.  All original parts were retained and can be reinstalled.

The purpose of the post is to report on the condition of the sponge
valves within the secondary valves.  These valves are now on my work
bench as I recover the stack pneumatics.  I had planned to also return
these valves to their original design using new leather surfaces.

As I started checking the condition of the sponge valve bodies
within these valves, I found that they are as supple as they were
when I first installed them 20 years ago.  None show any sign of aging.
Most impressive, is the fact that they are all still 100% air tight.
By mouth, I can draw a vacuum on the valve, wait several seconds, and
the vacuum is still in the tiny valve chamber.  No leather valve is
ever that air tight.

In my earlier days, I offered sponge valve kits to retrofit the cross
valve Duo-Art.  That system worked great, but it was met with great
skepticism.  Later, I developed the sponge valve system for the Ampico
secondary valves.  My approach to the use of these "new" materials was
just another option.  I never insisted on it, but I offered it for
those who wanted to give it a try.

Bad experience with the "Perflex" pouch, the new Aeolian sponge valves
of the 1970's, and other issues made the atmosphere for experimentation
less than welcome.  But my selected sponge material was not of that
same cheap stuff that Aeolian used that hardened almost overnight.
Through a multitude of gasket manufacturers in the Chicago area,
I found two that gave me great advice on product selection.  Now,
almost 30 years later, their advice has proven to be true.

Not all foam sponge is created equal.  The stuff I bought is still
supple.  So my sponge valves, now 20 years old, are going back into my
Mason & Hamlin.  Yes, the original parts are still available, but what
I said many years ago about the sponge valves not failing, has proven
to be correct.

Unfortunately, I no longer know how to obtain the sponge material
I used.  The process for making it was expensive and may not be
available.  It was formed with a skin surface on both sides and came
in varying thicknesses.  It had a hardness rating which was SC-43.
Examples of this durable sponge in a somewhat softer form are found in
automobile door seals.  In my youth these seals were worn out in a few
years.  Now, cars 30 years old still have original seals in good
condition.

So I still have two pianos in my collection to demonstrate sponge
valves.  The other is the little Ampico Spinet which can be seen on
YouTube at  http://www.youtube.com/watch?v=Zp8Fvk7-F5g 

Leather valves are used in the majority of my collection, but I think
my experience with these two pianos with sponge makes a strong
statement.  The right stuff is okay.

Bob Taylor
Missouri