Julie Porter explains the benefits of zephyr over thin pneumatic cloth
(commonly called thin tosh) in her recent article.  I thought people
would be interested in real numbers so I got out my micrometer.

Thin tosh is around 0.007 inch thick, or "7 thou" to an engineer.
Zephyr can be a bit variable and my current stock is between 0.0015
and 0.0020 inch, i.e., one-and-a-half to two thou.  It is also totally
airtight without the use of any dressings.  It is the only material
that should be used for recovering a singing bird wind supply.

The surface of zephyr has a slightly waxy feel to it and after some
experimentation I found the best glue to use is traditional hot glue,
but well thinned down.  I have not yet found a leather thin enough to
compete with zephyr for all its applications, although I will try to
find some "Morton" after it was recommended by Julie.

Zephyr has many uses in addition to singing birds.  I find it is the
best material to use when recovering the long and narrow pneumatic
motors inside Celestina and similar organettes.  Also, it is the only
material that can be used when restoring the stacks inside many German
pianos, i.e., the ones which use envelopes rather than pouches.

Best wishes,
Nicholas Simons, GB

 [ MMDigest articles about zephyr skin are indexed at
 [ http://www.mmdigest.com/Archives/KWIC/Z/zephyr.html 
 [ Much disagreement is expressed over the material properties; for
 [ example, "There is good zephyr skin, and there is poor zephyr
 [ skin, and few suppliers and rebuilders know the difference."
 [ -- Editor (Robbie)