Switched from PVA glue to wheat paste on my last 12 books and the spines finally open flat
For my first two years binding I used straight PVA on every spine because it was quick and I could get a book done in one evening. Then last spring a binder at the Ohio Valley workshop in Columbus watched me press a finished book open and told me my spines were stiff because PVA dries hard and has no flex. I tried a 3 to 1 wheat paste to PVA mix on a test coptic and the difference was obvious, the pages lay flat and the spine still held tight after a week of opening and closing it. Now I cook a small batch of paste every Sunday, brush it on thin, and let each layer dry overnight instead of rushing. Anyone else mixing paste and PVA or do you run straight paste on your spines?
My grandma's cast iron skillet is the same deal, she never scrubs it clean and that seasoning builds up layer by layer until nothing sticks. Sounds like your wheat paste works the same way, thin coats over time beat one thick rushed job every single time. Rushing just never pays off with stuff like this.