Cleaning, during which unwanted material is removed while the original surface is preserved, may be the most critical process in the conservation of a painting. Solvents are the most important and widely used tool for the cleaning of paintings, and a large body of practical, experimental, and theoretical knowledge exists regarding the use of solvents. Recently, other systems, such as gelled resin soaps, have been introduced for the cleaning of paintings. There is much less information available on their use, effects, and mode of action. They generally are more complex than solvent systems. Resin soaps, unlike solvent mixtures, contain nonvolatile components and may leave residues after cleaning. Questions remain regarding the mechanisms and effects of cleaning, and possible effects and activity of the residues. One must consider the roles of the individual components and the nature of the residues in order to answer these questions. The authors examine some of the important individual components of resin soap systems and their roles during cleaning. It is concluded that the surfactant and solvating activity of resin soap mixtures is due primarily to the presence of triethanolamine (TEA). Further research is needed on the effects of the residues and the possibilities of minimizing them through reformulation or changes in the way resin soaps are used.