The purpose of the study carried out by the British Leather Manufacturers' Research Association for the British Library was the development of a method of treatment for deteriorated leathers and the development of a stable bookbinding leather. It was found that retannage of deteriorated leather with an aluminum salt, followed by impregnation with a polymer (in an aqueous solution or a solution in a non-polar solvent) and the application of a surface coating of an acrylic polymer/wax blend, strengthens the leather and reduces absorption of pollutants by 90%. It was also found that, since the absorption of sulfur dioxide and the deterioration of leather are directly related to the use of vegetable tannins, either alum-tawed or chrome-tanned leathers should be used for book covers, or vegetable-tanned leathers should be retanned with 2% aluminum before use for book covers. See also AATA 15-912 for related study and 21-1334 for entire proceedings. -- AATA