I found an interview! So now I’ve got some insight into how she crystallizes her books and what she uses.
“I grow the crystals by creating a super-saturated solution of Borax in boiling water. When water boils, its molecules expand. I place the book in the saturated solution when hot and manipulate the book to my liking. As the saturated water cools again, the molecules shrink and any excess Borax crystallizes. Once the solution has completely cooled and the crystals have grown on the submerged objects, I drain the solution and dry the object without disturbing its shape. The objects will hold their new, transformed shape when completely dry.”
So now I know what to do, I best get cracking!
All information I have gained is from the link below.