Effect of tempera paint composition on their superficial physical properties- application of interferometric profilometry and hyperspectral imaging techniques

Effect of a SO2 Rich Atmosphere on Tempera Paint Mock-Ups. Part 2: Accelerated Aging of Azurite- and Malachite-Based Paints

“…Table 1. For each pigment, Kremer and author's references, mineralogical composition (by means of XRD) and grain size (µm) according to Kremer supplier and to the authors [22], mineral phases identified in the mock-ups by XRD before and after SO 2 exposure of the temperas. E: egg yolk-based paints and R: rabbit glue-based mock-ups.…”

“…In fact, the particular mineral composition of natural azurite and malachite varies significantly between artworks produced at different times and places, and may be related to provenance [30]. In addition to the mineralogy, the pigment grain size also influences the color and other superficial physical properties, as demonstrated for azurite in several scientific papers [22,31]. These studies also highlighted the importance of the binder (type and content) on the physical properties of the paint.…”

“…All the pigments were supplied by Kremer Pigments GmbH & Co. KG (Aichstetten, Germany). Table 1 shows the commercial name, the mineralogical composition according to Kremer, and the mineralogical composition and grain sizes as determined by the authors [22]. Five azurite pigments were selected for this work.…”

“…As tempera paints are made by mixing inorganic pigments with a proteinaceous binder (e.g., egg yolk or rabbit glue) [18], the damage caused to them by atmospheric gases such as SO 2 must be studied from different perspectives, focusing on the changes induced by the pigments, those related with the binder and those produced by binder-pigment interaction. The literature reports that the appearance and surface finish of fresh unaltered tempera paints varied depending on the type of pigment used, the pigment particle size and the type and amount of binder present in the paints, as all these factors influenced the color of the paint and the roughness of its surface [19][20][21][22]. Other recent research has reported that the impurities found in the historic mineral pigments used in tempera paints might significantly alter their optical, chemical, and physical properties [22][23][24].…”

“…The literature reports that the appearance and surface finish of fresh unaltered tempera paints varied depending on the type of pigment used, the pigment particle size and the type and amount of binder present in the paints, as all these factors influenced the color of the paint and the roughness of its surface [19][20][21][22]. Other recent research has reported that the impurities found in the historic mineral pigments used in tempera paints might significantly alter their optical, chemical, and physical properties [22][23][24]. Although some research has been conducted on aged tempera paint mock-ups mainly exposed to artificial UV light and outdoor atmosphere, including direct sunlight radiation, very little work has been done on the effects of impurities and pigment grain size on their weathering processes [21,25,26].…”