There is a whole lore around neat's-foot oil.  This spelling of the
word is seldom used -- too much punctuation.

Neatsfoot oil was researched years ago by a fairly impressive
laboratory for the Organ Historical Society.  The pamphlet of that
work has been mentioned here not long ago.  The problem was the organ
industry was having our standard vegetable tanned leather last only
5-12 years before it was as useless as the 80-year-old leather now on
the instruments.

This research lab collected thousands of samples of leather from many
sources including 150 year old organ leather and did strength testing
on it.  They especially tested pouch leather.  They used artificial
aging simulating our modern smoggy atmosphere.  They compared this with
strength tests of modern fresh leather of various tanning methods and
various animals.

Most important of what they discovered was that chrome tanning
prevented leather decay.  The leather they found that had been tanned
leaving 3-4% chromium salts in the leather had been proven to last 50
years and counting.  The government began tanning with chrome in WW2,
to prolong life of leather bomber's jackets and other leather items.
Those items were tested and found to be unchanged from fresh leather.
Also they found that hairsheep skin lasted best with the exception of
Kangaroo skin which is not always available.

One of their tests was treating the older leather with neatsfoot oil.
They discovered that the oil did absolutely nothing to strengthen or
slow down the deterioration of leather of any age as was the common
belief by organ and player piano techs.

In my personal experience, neatsfoot oil serves no useful purpose in
this industry and in fact, I have had to releather many complete organ
chests when it aged some and began sticking the valves to the valve
seats.  Some of these were stuck so strongly that I had to really pull
the pouch boards away from the toeboards.  I also had to use a
degreaser on the valve seats where the oil had wicked into the wood.
While pipe organs use much less pressure (2"-6" water lift), that kind
of sticking will definitely prohibit a player from playing at soft
pressures and thereby prevent the piano playing piano or pianissimo
passages.

I test every piece of leather to see what its tanning method was.  We
make sure that anything we restore will last thirty years or more in
our shop and we hate surprises and hate warranty calls even more.

I have put up a new page on my "Technical Tips" page on my web site.
Please access the site and click the "Technical Tips" page.  Scroll
down to "Leather Pointers" at the bottom of the page.  Any problems,
let me know.

D.L. Bullock
St. Louis
http://www.thepianoworld.com/