Oil and Wax Relations
Chemically, oil and wax are “cousins.” If oil is stirred into melted wax, the two will readily combine. In this mixture the balance of oil with wax should be seen as a continuum. At one end of the continuum wax is added to oil to give the paint more body, but the properties and requirements of oil predominate. The paint film will still be flexible, but it will have to go through a drying phase before it sets up and becomes permanent -- in fact, the wax itself will somewhat retard the drying of the oil since it has no drying properties of its own.
At the other end of the continuum oil is added to wax, and the properties and requirements of wax predominate. The oil, however, lowers the wax’s melting temperature and makes it less hard. Artists who make their own encaustic often do so by adding tube oils to melted wax. This dilutes the strength of the pigment, resulting in a more subdued waxy finish. As long as too much oil is not added the paint film will still be hard, and it will set up and become permanent on cooling.
There is a danger, archivally, in making a mixture of oil and wax that is too close to the center of this continuum, in other words, where the amount of oil and the amount of wax are equal. At that point the binding and the adhesive properties of both wax and oil are so compromised that the film they form is very unstable, since it is not able to either dry or harden.
Wax in Oil Paint
Our Pigment Sticks are a very good example of a wax in oil paint. Because they are in stick form, they may seem to have a lot of wax. Actually they have very little wax -- less than 15% of the stick is wax. When molten wax cools, it retains the continuity it had in its liquid state and forms a uniform structure, binding the oil within it. But this wax structure is very weak, and the instant the stick is crushed by drawing it over a surface, the wax structure breaks down and becomes absorbed into the oil. Further manipulation with fingers, knife, or brush turns the consistency into that of a buttery oil paint.
Oil in Encaustic Paint
Here are three techniques in which the use of oil added to encaustic creates different effects:
Apply a layer of encaustic medium onto the support and fuse it. Scribe line work into the wax with a tool. Rub tube oil or oil stick onto the surface and wipe down, producing a sharp “etched” line and a tone (depending on how much of the color you wipe down) on the surface. Fuse the surface, encapsulating the oil. Different methods of fusing can produce a line that is very precise or subtly diffuse. Another layer of medium can then be laid down and the whole process repeated. A painting built up in layers like this uses the natural opalescence of the wax to achieve an unusual sense of depth.
Working encaustic over wet oil paint can accentuate and enrich the optical effects of the oil, especially if fused only briefly. A longer fusing can make the oil diffuse into the wax. Further fusing can cause the oil to separate slightly from the wax giving it an unusual mottled effect. The encaustic can also add textural marks that are sharper than those made from thickened oil paint. We should emphasize here, however, two points:
a) The oil film should still be wet. A dried oil film is not absorbent enough to hold the wax well. It is important to consider this if you are working on stretched canvas instead of on panel, since a wax layer is less flexible than an oil layer.
b) The wax should be fused in order to encapsulate the oil. If the oil is not encapsulated it will remain a separate layer, cut off from air, and will never dry. If the oil is too thick you can leave soft spots in the painting.
When oil paint is used over wax and fused, it can create even more pronounced effects than when the encaustic is used over the oil. The oil layer may pull apart creating crackle effects. The degree to which this occurs, of course, still depends on amount of fusing. Again, however, some fusing should take place. An oil film that is not fused into the wax will dry and adhere, to a certain extent, to the wax. But the greasiness of the wax may cause a separation between the layers over time.
These methods only scratch the surface of what is really an exciting combination of materials. Experimenting with the two mediums reveals a variety of unpredictable effects. If you want to discuss any of the above further, give us a call.