hot hide glue

[Stephen Birkett]

I should clear up a misunderstanding about this thread. I didn't
actually forward *any* message to Paul Poletti, rather in the course
of a message to him I mentioned the subject of misconceptions about
hide glue. This is a topic on which he has strong opinions and long
experience, hence the strong reply which I posted to the list
unedited. This was never meant as an attack on anyone on the
list...Paul never even saw the original posts. Nevertheless I think
there is much that he can pass on about hide glue use.

The addition of urea to hide glue does not affect the strength of
the bond, only the set time (the `badness' of urea is a common
misconception). Commercial liquid hide glues have enormous quantities
of urea added, so that the set time is extended to infinity...thus
these never actually achieve the cross-linking necessary for a bond.
Adding reasonable amounts of urea to increase the set time for
handling soundboard glue joints say is the correct procedure. Buy a
fast set high gram strength hide glue and make up a number of
bottles with different amounts of urea and hence different set
times. You can keep the stuff in small plastic bottles in the fridge
(don't put it on your hot dogs) in liquid form for many months.
Keeping the glue hot all day in a glue pot is what destroys the
proteins and makes it unusable the next day (just as your beef stew
is pretty bad after keeping hot all day). Then you choose the
strength you want and heat up the small quantity you need at the
moment. Very convenient and you get all the benefits that hide glue
provides as well.

The comments above are based on suggestions Paul Poletti passed on to
me a while back, and may benefit people on the list.

Stephen Birkett (Fortepianos)
Authentic Reproductions of 18th and 19th Century Pianos
Waterloo, Ontario, Canada
tel: 519-885-2228
fax: 519-763-4686