Book and paper conservators spend a lot of time thinking about cellulose.  Paper is essentially a network of cellulose fibers held together by hydrogen bonds.  What happens to those fibers and bonds during the life of a document or book affects how the material ages.  The treatments we design and implement in the lab also affect those fibers and bonds, for better or worse.  While the craftsman aspect of hands-on conservation treatment work is easy to recognize, it’s not always as obvious how much organic chemistry is also involved in our work.

Cellulose strand

Cellulose is a polymer, which means it is a long chain composed of linked molecules.  Cellulose is a natural polymer, while most plastics are synthetic polymers.  Depending on the type of celluose (e.g. wood pulp versus cotton), cellulose chains may be made up of just a few hundred molecules, or several thousand molecules.  So, while different types of paper may all look like “just paper,” there is quite a bit of difference below the surface, so to speak.

These are some images of paper taken with a Scanning Electron Microscope (SEM) when I was a conservation student at the University of Texas at Austin’s Kilgarlin Center for Preservation of the Cultural Record.

SEM image of handmade cotton paper

SEM image of machine-made wood-pulp paper

Can you see the difference between the fibers in the handmade paper versus the fibers in the machine-made paper?  The fibers in the handmade paper are longer and more intact.  Cotton’s cellulose chains are much longer than wood pulp cellulose chains.  Also, the process of making paper by machine chews up the strands even further and results in a shorter-fibered paper.  This usually translates into less strength and durability, although there are other mechanical and chemical factors which also affect paper’s strength and longevity.