I just came across some potentially useful information on the Photographic Historical Society of Canada's website. http://www.phsc.ca/ For restoring leather coverings and bellows, and to remove mould from an old camera, TALAS Leather Dressing is recommended. http://www.talas-nyc.com/ "This inexpensive mixture of lanolin and Neats Foot Oil is used by libraries as a leather dressing for book covers (any necessary applications of dye or glue should be done before applying the dressing)." "Potassium lactate (also listed on the Talas web-site under chemicals & deacidification) is used as a leather protection and means to neutralize mould and mildew. Using potassium lactate on bellows may dissolve leather glues. The British Library prefers potassium citrate instead (British Museum leather dressing formula)"