The birth of the technique
Miniatures on ivory first appeared in the eighteenth century. While they present stylistic variations depending on where and when they were executed, in general the technique is relatively uniform. Old treatises describe them as painting in gouache, a term that covers water-based pigments on ivory. The surface tension of the water creates a droplet and prevents the pigment from spreading uniformly across the ivory, which is why old treatises incorrectly described ivory as a “greasy and slippery” material which was de-greased using ox gall. In fact, the ox gall functioned to reduce the surface tension of the water, thus allowing the paint to spread more easily across the ivory. To ensure better adhesion to the support, artists sometimes created a slightly rough surface with polishing agents such as ground pumice stone.