So I just spoke to my friend who is a big deal pipe organ builder and
restorer. I said “what’s up with hide glue?” Well after listening him go
off for ten minutes I found out it is getting real scarce. Organ
builders supply houses have some stock but are saving it for their
customers. Seems a big plant in Louisville closed when the swine packers
got shutdown.

Anyway he said a lot of builders are switching back to fish glue. He
said it’s a switch back to fish glue because that’s what they used 300
years ago. Interesting.

https://journeymansjournel.wordpress.com/2017/05/20/all-about-fish-glue-and-
hide-glue/