Glue and books: Cold glue
Cold glue is the most ancient of glues.
It used to be made of water mixed with animal bones ground to powder.
Without this substance we would not have had any books.
And its purposes are manifold.
I think it is an underestimated contribution to civilization.
The biggest benefit is that it creates no stiffness.
Once it is dry the glue has no substance and no colour.
As you apply it, it is like water.
So it needs a lot of time to completely dry out.
It will only hold pages of 110 grs or less, preferably Uncoated.
Ink is greasy, so the watery cold glue will bounce of any surface covered with ink.
Once you apply it the glue needs to dry for 24 hours to get its tack.
There are variations of cold glue that will hold semi-coated paper.
And there are variations that can be force dried.
The biggest benefit is that it allows for a book to open completely without any stiffness in the spine.