Regarding gluing the shiny side of leather: Many skins are lacquered
on the shiny side after the process of tanning.  I make a habit of
laying the leather on a piece of one quarter inch thick plate glass
and sanding the shiny side with 100 or 80 grit sand paper.  I do this
to insure a mechanical bond.  Here is the principal involved:

If you have ever wondered how they get Teflon to stick to a pan even
though it is a nonstick surface, here is how it's done.  The aluminum
pan is oxidized to create a textured surface.  The Teflon is then
applied and a mechanical bond occurs.  In the same respect, lightly
sanding the shiny surface of leather will create a mechanical bond,
insuring a bond with the glue.

I am old enough to remember making clay ashtrays in grade school.  They
taught us to score the clay before joining two pieces to insure a good
bond.  Utilizing this principal I always score wood before gluing and
I always sand the shiny side of leather before gluing.  After sanding
leather, hot glue will hold well.

Another principal I follow is: the thinner the material the thinner
the glue.  So when gluing leather it is good to have glue that is thin
enough to run into the pores and sanded surfaces.  The glue should be
close the consistency of cream.

Hot glue is difficult to get used to.  It is best when it is fresh and
has a golden appearance.  When I glue bellows cloth I always apply a
coat, and then I peal the cloth away and then I apply a second coat,
because the cloth is thick enough to absorb a good amount of glue.
Then I iron the bellows cloth to insure that the glue is taken into
the fibers of the cloth to make a mechanical bond.

On the advice of Larry Broadmoore I have been using Hartz cloth on my
pumps for the past 25 years.  This cloth is manufactured for use to
replace convertible tops in antique car restorations (Mercedes, to be
exact).  Up until a few years ago this cloth was sold with one cotton
side and one synthetic side.  At this time it is only available in
synthetic (both sides).

I was concerned about the hot glue being able to hold on the synthetic
material.  By ironing the cloth as I have just described I can attest
to the fact that the hot glue holds just as well as if it were cotton.

This material is thirty-five thousandths thick.  This is the same
thickness as the original cloth used by Ampico for their pumps.  It
holds up very well over time and is very consistent.  I buy my Hartz
cloth through Bill Hirsh in Newark, NJ.  He sells restoration supplies
for Packards.

Paul Manganaro