Keratinaceous materials, including animal hair, have long been used in the manufacture of utilitarian and art objects. The cleaning of composite objects constructed of hair attached to water-sensitive material now presents a challenge to conservators. In recent years Pickering particle emulsions and cyclomethicone have been used with great success in the cleaning and protecting of water-sensitive painted surfaces. Through a case study of the treatment of a 19th century hearth brush (1958.2326) from the Winterthur Museum collection, this research assesses the use of Velvesil™ Plus emulsions and D4 cyclomethicone, also known as D4 silicone solvent, in the aqueous cleaning of natural hair bristles attached to a wooden substrate. To test the effectiveness of Pickering particle emulsions and cyclomethicone in the treatment of hair, a soiled hair sample from the Winterthur hearth brush was trisected. One section was left uncleaned; a second cleaned with 10% deionized water in Velvesil™ Plus and D4 cyclomethicone and left unrinsed; and the third cleaned with the same solution and rinsed with D4 cyclomethicone. The three samples, representing the hair before, during, and after cleaning, were analyzed using scanning electron microscopy- energy dispersive spectroscopy (SEM-EDS), secondary electron imaging, and false color elemental mapping to asses the ability of the emulsion to remove embedded grime, to identify residual cleaning agents, and to visualize possible damage to the hair structure. Results showed the Velvesil™ Plus emulsion effectively cleaned the hair with minimal residues and no damage to the hair’s microstructure. The cleaning system was then applied in the treatment of the Winterthur hearth brush. The complete cleaning method included saturating the bristle bundles and wooden bristle board with silicone solvent to prevent the emulsion from absorbing into the wood and preventing the swelling and trapping of residues. The Velvesil™ Plus emulsion was then applied by brush and cosmetic sponge and rinsed from the surface with additional applications silicone solvent. This treatment method showed a drastic macroscopic improvement to the hair’s color, sheen, and pliability based on overall visual examination after treatment. A Pickering particle emulsion cleaning system combined with cyclomethicone masking of sensitive material is a promising method for the treatment of hair in composite objects, allowing for careful and controlled cleaning of soiled keratinaceous materials.
