LONG-TERM PHOTOAGEING OF SOLUBLE POLYAMIDES USED IN CONSERVATION OR IN MODERN SCULPTURES

The prediction of long-term ageing of synthetic polymeric materials used for conservation of artifacts can be based on artificial ageing experiments. The controversial example of 'soluble nylon' is re-examined. It is shown that the loss of solubility and the physical deterioration of these coatings is not due to hydrolysis, as previously proposed, but is the result of photothermal and thermal oxidations. These reactions can be inhibited through the introduction of a redox antioxidant, and a large extension of the polymer lifetime can be obtained.