Leather Conservation

Red Rot

 

Red rot, also known as leather rot or red decay, is one of the most difficult issues to deal with when working with leather. It is the deterioration of the leather into a powder. The powder leaves rust colored stains on almost any material or object it touches, hence the term, "red rot".

 

Red rot is not fully understood. However, it is linked to strong acids, particularly sulfuric acid. It may be that these acids were added during the tanning process, but they also could have been formed by the absorption of sulphur dioxide from pollutants in the air. 

 

Leather that is badly affected by red rot can become a powder simply by brushing up aginst it. Vegetable-tanned leathers from the late 19th and early 20th centuries are the most susceptible to red rot.

 

Dealing with Red Rot

 

Unfortunately, red rot is irreversible. Adhesives do not stick to the powdery leather and repair is impossible. The material simply rots away.

 

It is important that books and objects with red rot be isolated from other books and objects, as pictured to the left. It is also possible to isolate red rot by wrapping the item in acid-free paper or by creating a book jacket in the case of books with red rot.

 

Coatings can be used to try to stop leather from turning into powder. Though they are not a cure for red rot, they can consolidate the surface temporarily. These treatments (listed below) are only recommended for items that are in circulation or in research collections.

 

*A conservator should be consulted for books from special collections.*

 

Temporary treatment:

 

• Cellulose Ethers
   

  • Hydroxypropylcellulose AKA Klucel
     

  • Hydroxypropylcellulose and isopropanol AKA Cellugel