Photomicrograph: Resist residue
Tiny white particles, possibly residue from a resist, appear across the surface of Campfire, Adirondacks. When viewed under a microscope, these particles appear as angular white chunks embedded in the watercolor layer.
Scientific analysis indicates that these particles contain lead white, a drying oil, and possibly a minor resinous component. Although resists were not yet available commercially in the 19th century, several recipes composed of various combinations of beeswax, egg, resin, turpentine, lead white, and other pigments appear in artists’ manuals. Homer may have mixed a resist according to his own specifications.
Photomicrograph of Campfire, Adirondacks, showing white particles, possibly a resist residue, embedded on the surface and washed over with dark red watercolor. Original magnification 8x.