The roles of various components of resin soaps, bile acid soaps and gels, and their effects on oil paint films

Abstract

Mixtures that contain one or more of some common components of aqueous resin soap cleaning mixtures—organic resin or bile acids, an amine that is used to form the acid salt (soap), and a gelling agent—were prepared in order to determine the contribution of each component to the action of the soap formulation. The effect of these mixtures on paint films was examined by evaluating changes in paint film samples after treatment. The study included measurements of changes in color, gloss, mass and thickness. The amount of fatty acids extracted by each formulation was determined. Scanning electron microscopic (SEM) examination of the treated surfaces and of cross-sections through the samples was also performed. The results provide a means of evaluating the function and effects of each component, and may suggest changes in the formulation and use of these soaps. The optical measurements show that exposure to a mixture containing any of the components (all of which are non-volatile) results in a darkening of the paint film, probably due to saturation of the film with residual material. Residues are visible in many of the SEM photomicrographs. Extraction measurements show that triethanolamine is the component most active in removal of material from the paint films, with the resin or bile acid component having minimal effect. Triethanolamine also produces changes in the paint surface that are visible in the SEM photomicrographs, causing a permanent softening of the paint, film that extends below the surface. Gelling produces mixed results, reducing the effectiveness of strong mixtures and increasing the effectiveness of weak ones. The removal of material by gelled mixtures may be due to a combination of the surface activity of the gelling agent and the mechanical action required to remove the gelled mixtures.