Scientific investigation into the water sensitivity of twentieth century oil paints

A molecular study of modern oil paintings: investigating the role of dicarboxylic acids in the water sensitivity of modern oil paints

“…A related study identied a strong relationship between water sensitivity and pigment type: paints formulated with zinc oxide and/or lead were consistently non-water sensitive. 14,19 The study also demonstrated that in general, water sensitive paints were not associated with a higher degree of oxidation compared with non-sensitive paints, although some highly oxidised paints (mostly containing Fe and Mn pigments) were oen noted as water sensitive. 14 In general, irrespective of the overall degree of oxidation of the paint, water extracted a relatively higher amount of free dicarboxylic acids from water-paints than from non-water sensitive paints.…”

The concentration and origins of carboxylic acid groups in oil paint

“…Having established that autoxidation is dominant at low RH, we investigated high RH conditions and increasing ZnO concentrations because these factors likely promote ester hydrolysis. A number of recent publications have already demonstrated the relationship between the presence of ZnO 15 or high RH conditions and the formation of organic acids in paint extracts. 14,16 We compared LO-ZnO-TiO 2 and rLO-ZnO-TiO 2 paint models cured in dry (12% RH) and wet conditions (77% RH).…”

“…3 Furthermore, COOH groups indirectly determine the extent of metal soap formation, because before metal soap crystallisation can occur, networkbound COOM need to exchange with free SFAs. 5 Although many [8][9][10][11][12][13][14][15][16] have studied extractable acids, the concentration of COOH groups linked to the polymer network has, to the best of our knowledge, never been quantied.…”

Two-step analytical procedure for the characterization and quantification of metal soaps and resinates in paint samples

“…To confirm this hypothesis, a solution containing tridecanoic acid trimethylsilyl ester in iso-octane (8.0 µg/g) (obtained after derivatization with HMDS [23]) was analysed in triplicates before and after drying the solution under nitrogen flow and reconstituting the solution with iso-octane. The areas of the chromatographic peaks were compared using a t-test (CI 99%) and resulted to belong to the same statistical population.…”

“…Formation of metal soaps, fatty acid efflorescences, drips, ooze and melting impastoes, and development of solvent sensitivity are important conservation issues in modern oil paintings [22][23][24][25]. Their molecular causes, the kinetics of their development, and mechanical implications are still object of open debate among the scientific community.…”