When The Seven Stories Children's Book Centre bought three of my Selkie pictures, I donated a Selkie rough, the dummy and a sketch book. I was concerned to find, when I looked them out, that there were yellow stains on some pages of the dummy and sketch book where I'd used a glue - probably any old glue I had to hand - Pritt Stick maybe - not thinking about long term consequences. I consulted a paper conservator and was told the stains could probably be removed. The safe glues he recommended were: Shofu starch paste which has to be made up fresh each week and if I wanted something that was less bother to make up, then sodium carboxymethylcellulose. Both are available from Conservation by Design.
Conserving artwork is one more thing to think about but, one day, it will be worth it.