Effects of Humidity on Gessoes for Easel Paintings

Abstract

Gessoes are widely used in easel painting as grounds or preparatory layers; in art conservation, gessoes are employed as infill materials to level a loss in the paint surface in preparation for inpainting. The goal of this investigation was to establish the relationship between the mechanical behavior of various gessoes when exposed to different relative humidities (25%, 50%, and 100%) and to compare modern commercial gesso products with a traditional gesso. The materials included two commercial artists' acrylic gessoes (composed of largely titanium dioxide and aqueous dispersions of acrylic polymers), two commercial spackling compounds frequently used in the conservation of easel paintings, and a traditional gesso (calcium carbonate and rabbit skin glue). Uniaxial tensile testing was used to characterize the elastic modulus, strain at failure, and ultimate tensile strength (UTS) of the materials. By understanding the physical limits of these materials under different conditions, damage to artworks and the failure of conservation treatments containing these types of materials may be prevented or reduced.

DSC on ovalbumin-hematite “tempera” paints: the role of water and pigment on protein stability

“…Historical paint artworks may exhibit conservation issues due to degradation processes that may establish upon ageing, and that depend on several factors. Among them, a relevant role is played by the humidity conditions and/or exposure to moisture during certain conservation treatments [2][3][4][5][6][7][8][9]. Therefore, museums and galleries dedicate efforts into controlling relative humidity and temperature values at exposition sites, as well as in storage facilities, and optimal conditions are object of research [10,11].…”

After the paint has dried: a review of testing techniques for studying the mechanical properties of artists’ paint

“…Some of the studies shown in Table 2 focus on other materials found in the multi-layered structure of a painting than paint. Researchers have studied the response of grounds to RH to determine ideal storage conditions and the effects of drying shrinkage on the formation of cracks within the ground [52,56]. The stiffness of canvas as a function of the orientation of the weave of the sample has also been explored using uniaxial extension, demonstrating that the stiffness is strongly dependent on the orientation that the load is applied to the canvas [53].…”