Shoutout to the weird glue I found at a flea market in Cleveland that actually worked on vellum
I was binding a small poetry book for a friend and used this old, unlabeled jar of adhesive on the vellum spine lining as a last resort, and it set with a perfect, flexible hold without any discoloration, so has anyone else had a lucky find with an unknown material that turned out great?
That sounds like a recipe for disaster. Old glue can dry out or become acidic over time, damaging the paper. I would never trust an unlabeled adhesive from a flea market on something important like a book project.