Diving into micro- and macroscopic properties of egg-tempera paint based on Sienna pigment

Abstract

Egg-tempera painting was a pictorial technique widespread in the Middle Ages. In this work, Sienna earth and yolk have been used to formulate tempera paints according to historical recipes. Micro- and macroscopic properties were investigated to understand the interactions between the pigment and the binder. The pigment, inorganic part of the paint, was characterized by X-Ray Diffraction (XRD), thermal analysis (TG-DTA), Fourier Transform Infrared (FT-IR) Spectroscopy, granulometry, as well as Scanning Electron Microscopy (SEM). Then lecithin adsorption onto pigment particles was probed to understand yolk interaction with Sienna earth, pure kaolinite and goethite particles. NMR-Relaxometry was used to investigate the behavior and accessibility of the mineral surfaces to yolk and water. Macroscopic rheological properties of the paint systems were finally investigated.