Application

Supports

Because of the brittle nature of encaustic paint, it is best used on a rigid support, such as a panel or sturdy sculptural surface (see grounds for suitability). The Fayum portraits were painted on thin, slightly curved wood planks. Planks, however, have a tendency to warp or crack. To avoid this, modern fabricated boards, such as ¼" untempered masonite braced with a wooden frame in the back can be used. The edges should be protected with wax to prevent their becoming crumbly. Plywood can also be used, keeping in mind the off chance that the plies could separate over time. Both masonite and inexpensive plywoods are porous and hold a ground very well.

Stretched canvas is often used, but over time the rigidity of the wax causes the paint to crack as the canvas flexes with changes of temperature and humidity. Also the weight of the wax, if applied thickly, will cause the canvas to sink in the center.

Grounds

The main concern regarding a ground for encaustic paint is that it is porous enough for the encaustic to adhere to. Never use acrylic gesso or oil primer. They are not porous enough for this purpose.

The Fayum portraits were often painted over the raw wood itself. They were worked opaquely up from dark to light tones. A gesso ground of hide glue and gypsum was also used.

A gesso ground of hide glue, chalk, and white pigment (similar to that used in the Fayum paintings) provides a surface that is both smooth and porous. But this is a slow, tedious ground to prepare. A step by step guide to creating a gesso ground can be ordered from R&F Handmade Paints.

To test the suitability of an unfamiliar ground, apply paint to a test piece and set it aside for a few hours. With a chisel or scraper try to pry the paint off. If it comes off cleanly, it is not being absorbed into the ground. For greater assurance, freeze the test piece for half an hour before testing.