Tom Gregory mentioned his preference using cotton cloth over silk.
In my own experience I've found many a pneumatic covered in both, as
well as in Bilon, synthetics, etc.  Without a doubt, cotton cloth and
hot hide glue is always my first choice, but not because I question the
quality or longevity of the material itself -- it's the glue I don't
like to work with.  And I especially abhor the removal of "caulk like"
rubber cement type glues to whatever wood it was slathered onto.

I'm wondering just exactly how well the actual glue will hold in the
first place.  Usually the material itself peels off quite easily but
what a gawdawful job it is to sand down to bare wood.  Show me a glue
that will hold the cloth in place but not cause a sander disc change
after every other pneumatic and I'll buy it.  I _do_ like the look of
modern synthetics and trust that most available today are as good if
not better than the cotton standard cloth.  I suppose only time will
tell.

I've never been dissatisfied with traditional cotton cloth from Schaff
and especially like the wine colored motor cloth from PPCo.  As long as
those materials are still available I'll keep the glue pot warm.

Eric J. Shoemaker
Tacoma, WA