The Metamorfoze program, a Dutch program to preserve and digitize archives and publications, published a damage atlas of archives (PDF). The atlas was published ten years ago but the contents are still relevant today.
The atlas gives an overview of the type of damage archival records can sustain:
- binding and block damage, such as warping or spine damage
- chemical damage, such as fire damage, ink corrosion, and acidification
- mechanical damage, through use or violence
- pest infection by insects or rodents.
The atlas is illustrated with photos of examples of each type of damage, using Dutch archival records.
I have encountered most of these situations in my research, especially when doing on-site research. Most digitization projects start with a conservation project to stop and repair the damage, so digitization can capture as much as possible of the surviving information.