The appearance of small, rust-colored spots on the paper of old books and prints is a condition known as foxing. These spots can range in color from pale yellow to dark brown and are most commonly found on the pages, endpapers, and edges of the book block. While the precise cause is not definitively known, it is generally attributed to a combination of factors, including fungal growth, oxidation of iron particles present in the paper, and acid degradation. For example, a 19th-century volume stored in a damp environment may exhibit extensive spotting across numerous pages.
The presence of this discoloration can significantly impact the aesthetic value of a book, potentially reducing its desirability to collectors. While it generally does not compromise the structural integrity of the paper, severe instances can be visually distracting and considered undesirable. Historically, the perceived importance of its removal has varied, with some collectors viewing it as an inherent characteristic of age and others seeking restoration to eliminate its presence. Understanding its causes and characteristics is vital for proper preservation and conservation efforts.
