Greetings from Swan Hill, Australia.  Hide glue is available from
Leiner Davis Gelatine, Beaudesert, Australia 4258.  Their Australian
phone number is 07 554 13544.

Davis Gelatine has been providing Australia with hide glue "for ever".
They are now owned by the American company Leiner.

I buy my joiner's pearl glue in their minimum size bag which is 10 kg.
I am a professional piano/player restorer and can recommend their
product.  They must have an outlet in the States.  It might be worth
checking if they have a web site.

Regards,
Brian Butler