In the Studio: Painting with Terra Sigillata

Pioneered by Betty Woodman, using terra sigillata as a painting medium is an alternative process to its use on clay (1). Betty layered terra sigillata with acrylic paints, graphite, colored pencils, and wax on paper, creating mixed-media compositions. The wax layer was used to preserve and protect the terra sigillata while also serving as a buffer for the painting in a frame. Working on paper is essential because the terra sigillata requires a porous surface to adhere to. Gessoed canvas prevents the terra sigillata from soaking into the surface. Wood panel, un-gessoed canvas, or plaster can be experimented with as each of these materials have some level of porosity to them.

1 Terra sigillata painting: yellow ovals (Grolleg kaolin base terra sig. with yellow iron oxide), large gray circles (OM 4 ball clay base terra sig.), and smaller peachy orange ovals (Newman Red base terra sig.).

2 Watercolor Layer #1: Pale teal circles applied to watercolor paper in a repeating pattern and then dried.

3 Watercolor layer #2: Dark black circles are followed by pale green swatches. Some of the black blends into the green.

4 Terra sigillata layers: Yellow ovals using Grolleg kaolin base with yellow iron oxide, Newman Red base orange dots.

5 Watercolor layers #1, 2: Medium-sized teal circles were applied and dried, then grids of black dots were added.

6 Watercolor layer #3: A leafy green swatch of watercolor was partially washed over the pattern and dried.

7 Terra sigillata layers: Oval patterns of peachy orange Newman Red base terra sigillata were applied next.

An extended version of this method can be done with a mix of watercolor paints, terra sigillata, and watercolor paper. Watercolor paper is ideal as it’s a heavy-weight, porous paper material. First, apply the watercolor layers (see 2, 3 and 5, 6). Allowing each layer to fully dry before applying another layer can aid in creating successful compositions. After the watercolor has fully dried, apply terra sigillata using brushes or whatever method of application interests you (see 4, 7). This is a great process to experiment with application methods. The porosity of the watercolor paper allows the terra sigillata to soak into it, making a surprisingly secure adhesion. You can even bend the paper and the terra sigillata remains flexible, moving with the paper and not cracking off. Because the terra sigillata is in its unfired form, you can consider burnishing the surface for added sheen contrast in your compositions. Alternatively, the terra sigillata could be applied first, allowed to dry, and then watercolors could be added. In this second method, the terra sigillata acts as a resist similar to the way rubber cement or wax work as resists in traditional watercolor painting processes. If you’re feeling particularly adventurous, you could continue layering with ink, technical pens, acrylic paint, or wax. Keep in mind some terra sigillata will release if too much water is applied.

Rhonda Willers is the author of the new book Terra Sigillata: Contemporary Techniques, which is available at


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