Evaluation of the oxalic and tartaric acids as an alternative to citric acid in aqueous cleaning systems for the conservation of contemporary acrylic paintings

Today, acrylic emulsion paint is widely used in the artistic area as an alternative to the traditional oil painting. However, after a short time of painting exposure to the environment, the acrylic tends to accumulate surface dirt for inherent reasons to its composition. This phenomenon creates a conservation problem, because the usual cleaning methods are hindered by the acrylic film soft morphology and its high sensitivity to organic solvents. To date, few aqueous solutions based cleaning systems have been investigated as alternatives to the traditional methods. This paper proposes the use of oxalic and tartaric acid solutions for acrylic paints cleaning as alternatives to citric acid. A series of titanium white acrylic paint films were subjected to immersion tests in different aqueous solutions and their weight change was monitored to determine the effects produced by the solutions according to pH (3.5, 5 and 8.5) and conductivity (4, 6 and 12 mS cm−1). Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), X-ray diffraction (XRD), and scanning electron microscopy (SEM-EDX) techniques were used to evaluate the acids effects on the films before and after the tests. The results obtained showed that oxalic and tartaric acids exhibit similar properties to citric acid, resulting as a valid alternative for aqueous cleaning treatments on acrylic paintings.