I made a note in the spreadsheet to come back to those volumes once I had read up on a condition found in many collections of leather bound books, called red rot. My note has caused some alarm, perhaps conjuring up visions of a rampant red menace eating its way through precious volumes.
Red rot is a deterioration of leather binding, although experts don’t know for certain what causes it, 19th century tanning processes and pollutants play a part. Another intriguing factor may have been improved agricultural methods that produced larger animals, from a book-binding point of view this produced a poor skin quality. These factors, it is thought, have contributed to an inferior quality bookbinding leather in the late 19th century.
Although still not certain that this is red rot, as a precaution the volumes in question will be wrapped in acid free tissue and boxed hopefully slowing down any further deterioration.