Encaustic is one of the oldest forms of painting and is derived from the Greek word enkaio «burn in». This painting was created around 3000 years ago in ancient Greece when shipbuilders used a mixture of resin and wax to seal and impregnate ship hulls. By embedding the pigments in the wax medium, the color strength was preserved.
It’s very difficult to replicate ancient encaustic recipes. An interesting article about technology of ancient encaustic medium was published in Microchemical Journal by Elsevier in 2017: