Archival Characteristics of Encaustic
Part II: I wanted to explain some of the properties of encaustic and provide a guide for understanding more about the medium for artists, galleries and buyers/collectors.
Good adhesion is one of the most important characteristics of an archival painting. Encaustic has excellent adhesive properties. When working in encaustic the artist brushes on layers of wax which are heated and fused into one another. Most of the encaustic work I make is on wood, metal or paper. On wood and paper the first few layers are heated into the substrate. The paper or wood literally soaks it in like a sponge making adhesion even stronger. In metal pieces adhesion is still high, I have never had a failure. I take care to give the metal a lot of tooth before beginning to encourage the adhesive qualities of the beginning layers giving them something to hold onto.
Encaustic is impervious to moisture. Colors mixed or encased within layers of encaustic will not yellow or change over time. Therefore, pigments will retain their original luminosity for years to come.
As it cures, a process that takes about 1 year from the date the painting was completed, encaustic actually gets more transparent. When on display, plain Beeswax on its own will sometimes get cloudy blooms, making the work less transparent. Not so with encaustic. Encaustic will not get cloudy over time. This is because encaustic medium is not only beeswax, but also is made with a resin.
Encaustic medium is made up of just 2 main components: Purified beeswax and dammar resin crystals. Dammar crystals are a natural resin, a tree sap, that when thinned with turpentine traditionally made dammar varnish. Dammar varnish is a common final coat to traditional oil paintings to seal and protect them as well as drastically increase the luminosity of the colors underneath.
The dammar does a few key things to the properties of the wax.
- Dammar acts as a hardener, making the wax stronger and more resistant to abuse.
- Dammar increases the melting point of the beeswax to above 160 degrees. Making the medium stable in a variety of conditions.
- True encaustic medium made with dammar will not get cloudy over time. As the piece cures over a period of about 1 year (from the last time it was heated) the surface will become more clear. It will also hold a higher sheen when buffed.