I have read with interest the discussion of leather vs. rubber cloth
on mechanical vacuum pumps.  The Autotypist, Otto Schulz' version of
a player piano typewriter, used leather on the pumps.  These units ran
up to eight hours a day five and often six days a week, continuously.

I had one location that I took care of and they had two shifts a day
and the machines logged 16 hours a day.  The factory used a high grade
of leather that they obtained from the "Chicago Leather Company" or at
least that is what my old list of suppliers says.  Whether or not they
are still in business is anyone's guess.

The biggest problem with these pumps was not the leather wearing out,
which it eventually did, but the screws which held the bellows to the
cast aluminum frame that formed the basis of the pump.  The connecting
rods, strips of heavy canvas belting, also tended to wear before the
leather.

On a visit to the factory I observed the women covering the pump
bellows coating the leather with -- you guessed it -- rubber cement
thinned down just as the Ampico literature suggests.  The leather had
been glued and then stapled to the wood.  The coated bellows were
allowed to dry over night.  They did not use talcum powder on the
finished product.

Since the pump frames were open it was not too difficult to replace
one or more of the bellows as they were held on by four or six screws,
I cannot remember how many.  At any rate it was much easier than
changing out the bellows in an Ampico or Duo-Art pump.

Ed Gaida
egaida@txdirect.net