Paints binding media

PEGs have a plasticizing effect on lacquers and some paint-binding media. This effect makes it inadvisable to brush or spray PEG solutions on a painted surface. Even treatment with PEG of unpainted surfaces of the object may endanger paint layers because the PEG may move inside the wood structure and eventually reach the painted surface. Such a one-sided treatment may not be totally satisfactory as dimensional stabilization. Thus, painted objects need another type of dimension-stabilizing agent. 

The most important component in the majority of paints is the binding medium, which determines the physical and chemical properties of the paint. Blends of binding media are often used to impart specific properties to the dry paint film or to suit a particular application method. The compatibility of chemically different types of binders is an important factor to be taken into account by the paint formulator. These properties will be modified, however, to a greater or lesser extent by the nature and quantity of the other components, more especially the pigment. The general characteristics of various binding media are given in Table 14.2. 

Keune K., Binding medium, pigments and metal soaps characterized and localized in paint cross sections, PhD Dissertation, University of Amsterdam, 2005. 

Spanish Renaissance panel painting coating layer, casein in the ground Egg white as binding medium 122... 

Each painter had his own technique the binding medium was thus prepared using different additives, giving rise to a variety of recipes for each technique. For example, it is believed that fig latex (a white liquid exuded by the fig tree) was commonly added to the egg tempera, and that animal or plant resins were added to oil- and wax-based binders. On account of their adhesive properties, these materials were used not only as paint binders, but also as consolidants in restorations, as ingredients in varnishes used to finish paintings, and as ingredients of mordants to apply metallic leaf decorations. 

K. Keune, E. S. B. Ferreira and J. J. Boon, Characterization and localization of the oil binding medium in paint cross sections using imaging secondary ion mass spectrometry, Preprints of the 14th Triennial Meeting ofICOM CC Committee for Conservation, The Hague (Netherlands), 2, 796 802(2005). 

For a pigment to be useM, it must be insoluble in the binding medium so as to form a suspension. Otherwise it may bleed into successive layers of paint and render itself out of the control of the workman or artist. For a dye to be useful, it must be soluble in a dyebath or at least able to be rendered soluble prior to use. These distinctions and their technical implications will be discussed later in this section. 

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