5 TECHNICAL STUDY: BINDER CHARACTERIZATION

Loose samples were taken from each icon and submitted to the Smithsonian Center for Materials Research and Education for FTIR analysis utilizing solvent extraction. Selected particles were extracted using ethylene dichloride or ammoniacal ethanol, which are effective in isolating the organic material from other inorganic compounds. The primary constituent of the samples, including both paint and ground layers, is proteinaceous. Earlier research indicates that the binder typically used was an animal glue (Weihs 1973). The confirmation of the proteinaceous binder explains the matte quality of the paint layers and corroborates their solubility parameters as detailed in earlier work by the author (James 1999).