• Andreotti, Alessia
• Lanschot, Jettie Van
• Vila, Anna
• Bonaduce, Ilaria
• Andersen, Cecil Krarup

Abstract

This study explores the materials used in the preparation layers of nine paintings from the Danish Golden Age as a first approach to understanding the variation in use of materials in the nineteenth century as well as the potential for their degradation. Paintings on canvas have traditionally been suspected to be particularly sensitive to high moisture levels because of the changing quality of materials in the nineteenth century. The explanations have partly included the mechanisation of production methods and partly a more experimental approach to painting. Additionally, collagen-based glue sizing of the canvas is suspected to respond dimensionally to changes in relative humidity. In this study, pigments, fillers and binding media in the preparation layers of nine paintings by different artists were identified using scanning electron microscopy with energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry. The study shows a relatively low degree of variation in materials used in grounds. Surprisingly, no collagen-based binder was found in any of the nine paintings, suggesting that the canvases were not glue sized. All paintings contained calcium, lead, a drying oil and egg, even though only few contemporary recipes in painter’s manuals included egg as an ingredient for preparation layers. These results suggest that the commercial producers of prepared canvas may not have followed the manuals that were written for painters. Egg may have been added in order to increase flexibility and durability of ready primed canvases that were stored and sold in rolls. Moreover, the egg–oil emulsion has the advantage of being more viscous than a pure oil paint and could thus be used without sizing the canvas, rendering the primed canvas less stiff and less responsive to changes in relative humidity. The advantages of using egg in the ground are obvious, and this use, as well as the lack of glue size, has implications for the long-term preservation of the paintings in changing environmental conditions. These results imply that these particular paintings might be less sensitive to relative humidity changes than expected due to the lack of hygroscopic glue.

Topics

• impedance spectroscopy
• scanning electron microscopy
• laser emission spectroscopy
• mass spectrometry
• Energy-dispersive X-ray spectroscopy
• Calcium
• durability
• gas chromatography
• Fourier transform infrared spectroscopy
• spectrometry
• drying