In pre- and early modern times, craftsmen appear to have left no technique unexplored to allow their objects to glow and glitter in resemblance of the work of the goldsmith, or to have them assume the appearance of many more precious or otherwise desirable materials. Precious metal, for instance, was imitated by gilding wood or copper, gemstones, and enamel were counterfeited with pastes, glass, and glowing oil glazes, marble was evoked on walls with various stucco techniques, and porphyry stone was imitated with oil paint on the backs of panel paintings. This list can be extended with countless other examples, all showing a similar interest in Ersatz; the imitation of mostly costly materials with usually cheaper substances that share similar optical properties with their precious counterparts.
This research looked to study a pivotal moment in this history of Ersatz where panel painting developed from gilded masterpieces imitating the work of the goldsmith into windows looking into the world, the actions of light on various surfaces rendered with meticulous skill and precision. In her doctoral dissertation, Marjolijn Bol proposed that this development in the history of panel painting—by virtue of its innovator often called the "Eyckian turning point"—can be understood better when studying it as part of the history of substitution. Accordingly, her dissertation, and subsequent research, focused on the material and technical implications of the production of premodern Ersatz objects in relation to the history of panel painting. Furthermore, Bol discussed the various ways in which the optical know-how generated by these practices was exchanged with natural philosophers of the time.
Largely unexplored however, both in her own studies as well as in existing literature, are the social and economical implications of the history of imitation: Who bought these Ersatz objects? Why were they purchased? And how were they valued? Marjolijn Bol looked to answer these questions by re-reading more traditional art historical sources, while, at the same time, comparing and contrasting information from texts not usually taken into account in art historical studies. This way, she hoped to elucidate how the art of Ersatz was valued on various levels—economically, socially, and as a tool for generating knowledge—in the fourteenth and fifteenth century, respectively.