An Investigation Into the Rapid Cracking of Oil Paints Used Over Glossy Acrylic Mediums
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Authors
Hallchurch, Katelin
Date
2024-10-04
Type
thesis
Language
eng
Keyword
art conservation , conservation science , oil paint , acrylic gesso , acrylic medium , oils over acrylics method
Alternative Title
Abstract
Despite recorded use of the “oil over acrylics” method by artists since the 1960s, in the spring of 2022 Golden Artist Colors, Inc. (GAC, Inc.) revised their recommendations for the application of oil paints over acrylic mediums on the basis of newfound research demonstrating the cracking of certain oil paint colours when layered thinly (0.05 – 0.25 mm) atop glossy acrylic paints and mediums. This cracking occurred rapidly, during the early stages of paint drying, just prior to the “touch-dry” stage. To investigate this phenomenon, paint samples consisting of select colours of GAC, Inc. Williamsburg Artist oil paints around 0.05-0.25 mm thick were layered over both glossy and matte acrylic mediums. Additional samples made with varying gloss concentrations (from 100% gesso to 100% gloss), polymerized oil paints, and smaller swatches were also used for study. These samples were analyzed visually, mechanically, and chemically with a variety of analytical techniques and tests (digital photography, Hirox 3D Digital microscope, optical and fluorescence microscopy, differential scanning calorimetry, adhesion testing, Fourier transform infrared spectroscopy, pyrolysis gas chromatography mass spectrometry, scribe testing, and environmental monitoring) to evaluate surface texture, crack formation, material composition, and the layer structures of the samples in order to piece together the behavior of this cracking phenomenon.
The results demonstrated that the oil paints were losing components of the drying oil to the acrylic underlayer prior to their initial stage of curing. Chemical analysis showed that paint samples exhibiting cracking have minor relative amounts of oleic acid: a highly cured, rigid paint film now sits atop a softer, gummier acrylic surface. Any further stresses in the system as drying continues are now likely to result in cracking. The exact cause as to why only certain colours are affected remains uncertain, however certain pigments are known to catalyze drying reactions in paint films and may possibly play a part in the rapid curing observed here. Such results and research hold value to both the paint industry, artists, and the general understanding of artist materials, impacting product usage, artist practices, and future research on paint mediums and “oil over acrylic” paintings.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International