Modern samples of pure cellulose nitrate are considered to be stable, due to better manufacturing procedures, purer starting materials, better removal of acid and increased knowledge of plasticisers/stabilisers. Possible treatments for stabilizing old, deteriorating samples were investigated. Ageing in all work used heat and humidity, and testing included using of the Bergman/Junk test, as well as the Oddy (copper discolouration) test. Tables and line spectra. Suppliers and references.