Cuerda seca, which translates from Spanish to “dry cord,” is an ancient technique for creating line decoration on pottery using a mixture of wax resist and a colorant. It is a great way to add definition to drawings because the wax resist keeps the glaze from covering up the lines.
In today’s post, an excerpt from the September/October 2020 issue of Pottery Making Illustrated, Marc Egan shares how he uses the technique to add definition to his nature inspired decoration. —Jennifer Poellot Harnetty, editor.
PS. Check out the September/October 2020 issue of PMI to get advice on glazing and firing cuerda seca decorated pottery!
Ecology, landscape, and our evolving relationship with the natural world have always been themes I’ve explored in my work. With my illustrated wall plates, I try to capture the beauty and energy of the cycle of growth, reproduction, decay, and regeneration in the garden. Drawing inspiration from plants, insects, fungi, and microorganisms in soil, I aim to recreate a world that is dynamic, strange, and beautiful. I use the glazing technique of cuerda seca, which involves painting lines on the bisque piece in a mixture of wax and iron oxide, then glazing the spaces in between to create the imagery.
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I start the surface decoration on each piece by drawing directly on the bisque-fired plate in pencil, roughing out the overall design. Though every design is unique, I’ve developed an extensive vocabulary of stylized imagery to be used in various configurations.
The excitement for me is in creating asymmetrically balanced but active compositions. I use rough paper cutouts to help plot the composition. These cutouts have the advantage of letting me see the shape, placement, and directional movement within the composition before committing to drawing it in place. As I plot out the drawing, I think ahead to how it will be glazed using the dozens of glaze colors and textures I’ve made for this purpose.
When I’m happy with my drawing, I apply the cuerda-seca wax-resist lines with a liner brush (1). The pencil drawing serves as a rough guide. As the wax lines are put down, make small adjustments so there aren’t many lines converging or overlapping in a tight space. Keep in mind that the process creates outlined glaze shapes. What looks good as a line drawing doesn’t always translate well in glaze. Too many converging lines create a patch of dry black clay with tiny bits of glaze in the unwaxed areas.
After completing the wax lines, set the piece aside to dry (2). Usually an hour is sufficient, but it shouldn’t be left for more than a couple of days as the wax and oxide mixture becomes less effective as a resist, making the glazing process slower.
Apply the glazes with a soft brush, loading up the brush and jiggling it over the area to be glazed (3). The glaze flows off the brush into the space and is contained by the wax lines. Slip trailers and squeeze bottles (4) work well when applying glazes on flat surfaces (e.g. tiles), but can be tricky to use on curved forms. The glaze goes on thick and pools within the wax lines on a horizontal surface, but will flow over the lines on any curved surface. The brush is handy for keeping the glaze in place until it sets up. I add 0.5% CMC Gum (dry weight) to my glazes to extend the drying time, which allows me to brush on the glazes evenly.
Usually each outlined section is filled in with a single glaze (5), but occasionally two or three blended glazes can be used for textural or modeling effects. One of the benefits of separating the glazes within a wax line is that different types of glaze can be used side by side. Because the glazes don’t overlap, no eutectics are formed, and problems such as running or bubbling are avoided.