Hi All,  My concern about using an iron as a panacea for creating
a good seal is not so much the possible damage to the rubber as it
is the breakdown of the proteins that give the glue its strength.
And while others have mentioned that there are smaller and/or better
(more controllable) irons available, the average novice will most
likely use a regular clothes iron.

In the instructions that come with every order of the specially
formulated hide glue (that I sell) is a paragraph which reads:

  "When working in a cool environment, the glue should be used with
  a thinner consistency.  If you then need the "death grip" effect of
  heavier glue, just apply a sizing coat on one of the parts and let
  it set up first.  When covering pneumatics, use thinner glue and a
  wide brush to keep the glue warm.  Put the cover around it before the
  glue can start to gel.  If you doubt your ability to use this glue in
  the time window allowed, just iron them down before completely dry.
  Double glue all large bellows and always iron their covers after
  they are well-set but not completely dry.  When you see tiny beads
  of reheated glue oozing out, you know that you have the right
  temperature and time with the iron.  Hot hide glue is just like
  solder.  A cold joint will not show up, sometimes for months, but
  it will always eventually fail.  When in doubt, reheat."

The instructions were written by Craig Brougher, who formulated the
glue.  What I would like to point out is that his instructions are
quite explicit.  Simply stating that one can use an iron to re-melt
the glue, and thereby create a better seal, is far too vague and could
lead to misuse of the technique by novices.

For the record, I had problems using hide glue early in my career and
it dawned on me that I could use an iron to reheat the glue.  Problem
was, I didn't know when 'enough was enough" and I ended up getting the
glue too hot and I squeezed out too much of the glue.  The end result
was a large bellows that failed the first time I tested it, and it had
to be completely recovered.  I'd like to help newcomers avoid the
mistakes I made, and that's why I wrote this posting.

Musically,

John A. Tuttle
Player-Care.com
Brick, NJ, USA