Let me first say that neither this posting nor the comments I have made
in the past are intended to be either for or against zephyr skin, but
are simply for your information.

Many years ago someone told me that zephyr skin was sheep intestine.  I
do not know this to be fact.  On my first post about zephyr skin I
noted that a pouch caused a cipher because the zephyr was composed of
two layers, and a hole in the inner layer caused air pressure to
communicate with an adjacent pouch.  I did not at that time know much
about zephyr skin, and I still do not know all there is to know.  I did
know that one of its earliest uses other than sausage casings was for
safes (condoms).

This week I saw a Maryland Public TV program on World War One
Zeppelins, which described how cow intestine was cut into lengths and
cut along an element to make rectangles which, when wet, can be
overlapped.  When these dry, they form a rather impervious continuous
sheet.  This process was used to construct the gas bags that held the
hydrogen inside the zeppelin frames. I do not know whether any
additional sealing agent was applied to the intestine bags used to hold
the hydrogen gas in the Zeppelins.

I have worked with hydrogen gas in testing fuel cells and fueling a gas
turbine which I converted to burn hydrogen.  Hydrogen gas (H subscript
2) is the smallest and lightest molecule that I know of and is not only
notorious in its ability to leak through the smallest openings but,
under pressure, will diffuse into iron or steel.  I seem to recall
using stainless steel to avoid hydrogen causing the tubing to become
brittle.  Hydrogen burns with a colorless flame.  The colors seen in
the burning of the Hindenburg were due to the bags, outer covering, and
aluminum frame burning.

If you examine wet intestine under an electron microscope, the best
description I can give is to imagine a one-quarter-inch outside layer
of a luffa sponge, with the skin of the gourd still attached.  The
intestine is of course made of epithelial cells or collagen, which when
wet, is somewhat gelatinous and, I guess due to this and its fibrous
nature, it clings and adheres one to the other.

All of this because I find zephyr skin and its applications interesting
and because of my deceased first wife's describing cleaning hog
intestine to make sausage.  Maybe this is too much information.

Allen Ford