Small, reddish-brown spots or patches commonly appear on older paper, particularly in books. This discoloration, often accompanied by a musty odor, results from the oxidation of iron and other compounds present in the paper pulp. The size and distribution of these spots can vary, sometimes resembling the shape of a fox’s pelt, which may be the origin of the term.
While often perceived as a flaw, this natural aging process can contribute to a book’s character and provide insights into its history and storage conditions. Its presence doesn’t necessarily indicate damage or fragility but is rather a testament to the paper’s organic nature and the passage of time. Understanding this process allows collectors and book owners to appreciate the artifacts in their possession more fully. The presence, or absence, of this phenomenon can even impact a book’s value in certain collecting circles.
