The bindery at the Cleveland library uses wheat paste and I think we all should
I stopped by the special collections room at the main library in Cleveland last month and watched their conservator repair a 1890s ledger with plain wheat paste and Japanese tissue. She said they quit using PVA on anything old years ago because it gets brittle and you can't reverse it. I have been mixing cooked wheat paste at home ever since, $4 of flour lasts me six months, and my hinges come out softer and they actually open flat. The tradeoff is it dries slow and you have to make it fresh or it molds. So what are you all using for historical repairs, or am I late to this party?
Wheat paste all the way! You're not late, most people just don't wanna bother with the mixing.
The mold thing is real though, I keep mine in the fridge and it buys me an extra week or so.