Sorry to re-open this icky sticky subject, but a serious question has
come from a Dutch organ builder, Henk van Eeken, who is restoring a
300+ year old church organ.

I quote his first letter to me below, but in further correspondence
Henk makes it clear that his concern is not whether cold hide glue is
strong enough (his experience, like mine, is that it is plenty strong),
but whether the two chemical additives mentioned in his letter could be
damaging to the wood in the long term, after a century or two (!).

Those of you who know glues and wood and chemistry, please offer your
speculations, and contribute to the restoration of a true antique.

Mike Knudsen

 - - -

Dear Mike Knudsen,

I am an organ builder in The Netherlands, and I read your very
interesting article 'Cold Liquid Hide Glue Is Strong' of June 24
last, 990624 MMDigest.

My team is restoring a so-called sound board of an organ of 1680,
and it speaks for itself that we only use hide glue for this purpose.
For some smaller connections we use the warm type, since we have a very
handsome electrical device with which we can pre-warm the wood very
easily.

For some large pieces, pre-warming the material is a real pain, so for
this application Franklin's Liquid Hide Glue could be a good solution.

In your article you are mentioning the additions ammonium rhodanate and
dicyanodiamide in Franklin's Liquid Hide Glue.  I wonder to what extent
these additives could have a bad influence on the sound board we are
working on.

Could you please be so kind as to inform me about what percentages of
each addition is in Franklin's Liquid Hide Glue?

Yours sincerely,
Henk van Eeken