I read the article by Bill Mackin and have the following comments.
I, too, believe in finding improved ways to rebuild and restore
mechanical instruments.  My philosophy has always been that the
materials used originally were chosen because the better stuff made
today, in some cases, was not available.

Some wisdom must be used in seeking new methods and materials.  In the
case of gluing pouches down, I have never seen an original installation
where hot glue had failed.  Nor have I ever seen an original installation
where the leather pouches, glued with hot glue, were difficult to
remove and replace.

Once a technician is equipped to work with hot glue, the fuss is over.
In gluing pouches, the operation is fast drying and easy.  Why on earth
then, would there be any need to experiment with a new glue agent when
the original method has proven 100% reliable?  Additionally, will the
silicone glue render the wood impervious to hot glue for future repair?

So as far as switching to silicone glue, I see no compelling need to
switch and I see the possibility of permanently changing the pouch
board to reject hot glue.  In other words, this new method is not
needed, and maybe has two downside factors.

As a sealant for the leather itself, one must consider that the design
of the bleed size is based on the porosity of the leather at the time
the machine was designed.  It follows, that if the porosity of the
leather is reduced, then the bleed size must be increased.  I think it
easier to seal the pouches in the traditional way, and not mess with
the bleed size.  Research within the pipe organ industry has found that
silicone does not in any way preserve the leather.

As I said at the beginning, I support developing new techniques, but
tampering with the bleed balance and 100% reliable hot glue, is not an
area that I would want to change. I am currently installing over 3,000
new pouches in my pipe organ and I will do it only once -- with hot glue.

Of course, if it all works out okay for Bill, then my note of caution
can be ignored.

Bob Taylor