A GC-MS study on the deterioration of lipidic paint binders

摘要

This paper presents a study on the degradation of lipidic paint binders induced by irradiation with UV light (365 nm), exposure to urban air pollutants such as NOx and SO2 and combinations of the various treatments. The characterisation of lipidic binders has been performed by a GC-MS procedure on a series of non-pigmented paint specimens prepared at the Opificio delle Pietre Dure-Firenze (Italy) and submitted to accelerated ageing. The results show that UV irradiation and exposure to NOx and SO2 increased the polymerisation and cross-linking of the paint thus facilitating the cleavage of fatty acid chains as a result of progressed oxidation up to the formation of oxalic acid. The presence of oxalic, malonic, succinic, glutaric, adipic, pimelic, OH-octadecenoic acids and cholestenes describes the behaviour of aged paint layers. In samples of paintings by Cimabue, Raffaello and Boucher, oxalic acid and oxidised carboxylic acids have been found, confirming the results obtained in the paint specimens. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 18]