Chemical characterisation of selected poly(vinyl acetate) artists’ paints using a multi-analytical approach

Despite recent, welcome efforts over the past two or three decades, aspects of the characterisation of modern paint materials remain a challenge due to their chemical complexity, difficulties in obtaining relevant reference materials, as well as significant variations in formulations and between paint brands over time. As paint constituents can influence ageing mechanisms, appearance, condition, and response to conservation treatment(s), it is necessary to continue to develop methodologies for the detection of constituents used in modern paints to inform paint manufacture history, treatment risk and preservation approaches. This research contributes by focusing on the chemical characterisation of poly(vinyl acetate) artist paints from the Tate Conservation and Heritage Science Archive , using a standard multi-analytical approach including elemental (SEM-EDX) and molecular (FTIR) analysis and analytical pyrolysis (EGA-MS and double-shot Py-GC/MS). This approach facilitated the detection of a wide range of polymers, pigments, fillers, and additives, in selected artists’ paints ranging from numerous classes of both internal and external plasticisers, solvents, coalescing agents, preservatives, fatty-acid surfactants, antioxidants, stabilising agents, lubricants, thickeners, protective colloids, as well as organic pigments (quinacridones, phthalocyanines, and azo types). A comparison between dried samples of naturally aged and contemporary paints from one extant brand has begun to inform key changes across one paint line over time. With respect to the paint binders identified, most consisted of a poly(vinyl acetate) homopolymer binder, with others also copolymerised with acrylates, with all examples employing a range of phthalate-based or more recently used plasticisers for contemporary paint formulations.