Perhaps you have visited a fine art gallery and seen some interesting paintings labeled as “encaustic on panel” or “encaustic and oil”. Just what does “encaustic” mean? Here’s a brief introduction.
Encaustic painting uses a thermoplastic process (medium is softened to liquid when heated, hardened to solid when cooled) that uses wax, usually 90-95% clear beeswax mixed with 5-10% damar resin (a hardener), melted to liquid state and then mixed with quality dry pigments and applied to a rigid panel, most typically wood or hardboard. The damar resin additive raises the melting temperature so the wax is less susceptible to heat damage, allows the encaustic to cure and harden over time so it is more durable, and prevents “blooming” (a whitish haze that can appear on the surface of a painting). Resin also results in a harder surface for polishing of the encaustic to a high gloss. The process repeats in layers until the final image is complete. Then the final image is carefully heated to fuse the layers together into a fully integrated whole.
The thermoplastic, fluid nature of encaustic is conducive to variety of application techniques and methods of manipulation. A distinctive benefit of encaustic painting is its durability due to the impervious (to moisture) characteristic of beeswax. Encaustic paintings do not need a glass cover or a protective top coating, and are very resistant to fading, yellowing and cracking. Encaustic painting is also a very clean process that is free of chemicals, solvents and the fumes associated with them.
I’ve found some very good descriptions of the encaustic technique of painting at the following websites that I recommend for you to read to gain a better understanding of this process:
The last link above provides a helpful set of FAQ answers that address encaustic paint durability.