Beaufort District Collection Connections: Relics with Red Rot in the Research Room by Cassandra Knoppel

For those who missed Cassandra's presentation and libation at her program on October 8, 2025... - gmc

In honor of ~spooky season~, we at the BDC wanted to touch on an "archival horror" potentially lurking in our collection, similar to our post on arsenic earlier this summer. This time, we're talking about red rot!

An example of red rot from
a book in the BDC's collection.

Red rot may sound like a fictional disease from Harry Potter, but in truth it is a plague upon 19th-century leather bound books and other historic materials made of leather. According to the Society of American Archivists, red rot is "the process of leather deterioration characterized by orange or reddish powder." Red rot causes the covers of books to decay, often appearing "...at the hinges of the book where the leather flexes" per The Library of Congress. First coating the cover with a fine, red dust, red rot can eventually cause the book's cover to crack and crumble into a powder. The red dust coats any surface it comes into contact with. Archivists who have encountered severe red rot have remarked that their work desks appear to be the scene of a crime, and by the stains on their hands, they are the culprit! Red rot can also cause the remaining leather to be incredibly sensitive to any moisture, resulting in permanent stains on the surface of the book if it becomes damp.

But what causes such a pernicious disease? Well, we aren't entirely sure. We do know that red rot is "most commonly found on vegetable-tanned leathers from the later 1800s and early 1900s" according to the SAA. Given that common thread, it is believed that acids, like sulfuric acid, used during the tanning or dying processes of the 19th century may cause the decay as these acids eat away at the proteins in the leather.

If this is truly the root of red rot, it would then be considered to be an issue of inherent vice. Grace likes to explain inherent vice as the "original sin" of archival materials, but the SAA officially defines it as "the tendency of material to deteriorate due to the essential instability or interaction among components." Basically, the composition of the material itself leads to its eventual demise. Acid is a well-known vice within archival materials; for example, paper, especially newspaper, has lignin which breaks down into acid, and the chemicals within cellulose acetate film break down into the vinegar-smelling acetic acid.

That being said, it is also speculated that red rot is actually caused by the accumulation of pollutants on the leather over the years, resulting in the creation of acids. These pollutants can include high heat and humidity, along with air pollution which contains nitrogen dioxide and sulfur dioxide. Either way, it is generally understood that high levels of acid in the leather result in red rot.

Red rot on the spine of two books in the BDC.

Since I was researching the topic, I decided to do a quick study of books from the BDC collection to see if we have any red rot issues. I did a quick scan of our stacks, comparing the spines and covers I saw on our shelves with the examples of red rot from Washington University Library's Identifying Damaged Materials to Send to Preservation guide. I was only able to find a handful of books with red rot (thank heavens!). The items I found had red rot occurring along the spines of the book and a bit at the hinges, if those areas were even still present on the book's cover given the decay. Most of these items already had their problem areas addressed by prior BDC staff, which leads me to my next topic - the treatment of red rot.

Many of you are likely curious about how we can go about curing books of red rot. Unfortunately, there is no real cure as books cannot be restored back to their prior condition once red rot has decayed them. However, there are ways to prevent further damage to the material and to prevent it from potentially damaging other items with its dust. In the BDC, we have treated our items by covering the spines and covers of red-rotted books with polyester dust jackets or storing them in archival book boxes. This is a cheap and easy way to protect our materials as recommended by professional organizations like NEDCC. Wrapping the book in acid-free archival paper is another solution to prevent the powder from coming loose during handling and rubbing off onto other materials.

Another method for treating red rot is to stabilize the material through leather consolidation, though this method is far more hands-on and should really be done by a conservator. Leather consolidation halts the red-rotting process by binding the leather fibers to each other, though it is not a permanent solution. One of the most famous leather consolidation treatments is called the "Red Rot Cocktail." This cocktail was created by CCAHA and combines Klucel-G, SC6000, and other additives to create a gel that can be brushed onto the surface of a leather object. Once it dries, the fibers of the leather will have adhered to each other, slightly darkening the leather but reducing the powdery residue of red rot. You can see an example of the application process of a leather consolidation treatment in Southern Book & Paper's video "Step 9: Consolidating Antique Leather. Book Conservation & Repair."

Beaufort District Collection's Red Rot Mock-tail Recipe

As a special spooky treat for our fellow book-nerds, my husband and I have created a recipe for a "Red Rot Mock-tail." Lauren Clark and Misty Kalkofen created an actually potable Red Rot Cocktail named after the non-consumable preservation treatment, but we wanted to create a more family-friendly version without alcohol for our library patrons. So, this recipe is inspired by the flavors of their recipe and still creates a vibrant red and delicious drink!

Ingredients:

1 qt. bottle of Cherry juice
3-4 oz. of Elderflower syrup (depending on taste)
1 52-oz. bottle of Lemonade
6 12-oz. cans of Sparkling water

To make a large amount (for a party or otherwise), combine the ingredients as listed into a 2-gallon pitcher. If you are making ahead, you can swap out the sparkling water for regular, non-carbonated water. Store in the refrigerator.

For a single serving, the ratio we like best is: