Encaustic is a beeswax based paint that is kept molten on a heated palette. It is applied to a surface and reheated to fuse the paint into a uniform enamel-like finish. The word encaustic comes from Greek and means to burn in, which refers to the process of fusing the paint. Encaustic has a long history, but it is as versatile as any 20th century medium. It can be polished to a high gloss, it can be modeled, sculpted, textured, and combined with collage materials. It cools immediately, so that there is no drying time, yet it can always be reworked. The durability of encaustic is due to the fact that beeswax is impervious to moisture. Because of this it will not deteriorate, it will not yellow, and it will not darken. Encaustic paintings do not have to be varnished or protected by glass. Encaustic painting was practiced by Greek artists as far back as the 5th century B.C. It was used in a variety of applications: the painting of portraits and scenes of mythology on panels, the coloring of marble and terra cotta, and work on ivory (probably the tinting of incised lines). The best known of all encaustic work are the Fayum funeral portraits painted in the 1st and 2nd centuries A.D. by Greek painters in Egypt.