Encaustic originates from ancient Greek meaning "burning in" thus heat is always required to qualify as this method. Different kinds of additives were experimented with to raise the temperature and strength of the waxes. Such as Punic wax where it is boiled in a solution of sea water and soda three successive times! Today most Encaustic medium is typically a ratio of Bees wax and Damar tree resin. The wax is then used in a molten stage either as is or pigmented then applied / adhered to a absorbant surface with heat to fuse it on to itself and the substrate.
The oldest artwork of Encaustic has been around since 100 BC to AD 300 from the Greco/Romano-Egyptian period specifically the Fayum Masks of Egypt. These masks remain some of the worlds most well preserved examples of Encaustic art. Found in the Fayum Valley of Egypt these masks were created for each person and then later put on their mummified self after death. Also, Byzantine Icons and ancient tiles, boats and sculptures often had molten pigmented wax or punic wax applied. Encaustic is one of the most archival type of paints being impervious to mold and water.