In the Studio: Ceramic Watercolor Surfaces Ruth Easterbrook

Appears in the Nov/Dec 2015 issue of Pottery Making Illustrated.

My love and appreciation of beautifully illustrated children’s books, especially the work of Beatrix Potter, Tomie dePaola, and Maurice Sendak, has strongly influenced how I approach my surfaces. These illustrators combine a realistic and scientific appreciation of nature using watercolor, which I adopted into my own work. Working on red clay, I layer terra sigillata mixed with Mason stains and a clear base glaze mixed with copper carbonate to achieve a similar effect with depth and intentional irregularity.

Terra Sigillata Layer

The varied surface comes from the naturally thin terra sigillata, which makes it easy to control how thickly it’s applied with multiple layers. If the terra sigillata is applied thinner, the red clay shows through, which creates a rich foundation for the finishing glaze.

To take advantage of the transparent quality terra sigillata can have when applied thin, I create textured surfaces using various sized serrated ribs. I scrape the surface in patterns, zigzags, and vertical lines. Beginning with this first step, I’m already planning what the piece will look like when it’s finished. In the recessed areas of the pattern, the terra sigillata will catch and pool, looking opaque. Where it remains thinner on the raised areas of the serrated rib marks, the red clay is visible, highlighting the rib lines and patterns.

Mason Stain Additions

Another part of my layering is tinting the terra sigillata with Mason stains. Mason stains are generally what-you-see-is-what-you-get, which allows me to use them similarly to traditional watercolors. I can decorate very specific areas, patterns, and designs, which will show through the final translucent glaze. I add stain to small batches of the white base terra sigillata to create my color palette. I can manipulate the finished look by layering the stained terra sigillatas directly over the red clay or over a base coat of the white terra sigillata.

Milky Glaze Layer

I use a final layer of glaze to accentuate all of the detail underneath. My base glaze contains only three ingredients. It’s a very reliable recipe that doesn’t craze or run and fires to cone 6. Additionally, what I like about this recipe is that it has a large amount of Gerstley borate, which adds a milky quality to the glaze when applied thickly, adding yet another layer to the surface.

In the studio I mix a five-gallon bucket of the base glaze. When adding the water, I tend to be conservative since I don’t want the glaze too watery. I sieve it twice, each time with a little more water. The final consistency is on the thicker side, like heavy cream. I mix it thick so I can control the layering with a brush-. First I apply an overall thin coat, then I brush small areas with thicker coats to create cloudy patches. If applied too thick, a cloudiness will cover any lines and detail underneath.

Oxide Additions

If I want to get yet another layer of subtle color, I add various amounts of copper carbonate to tint the base glaze. The hue that works best for my surfaces is three cups of base with 2½ grams of copper carbonate.

With this combination of surface treatments, I’m able to achieve the watercolor effect I love so much in the illustrated children’s books from my childhood.

Ruth Easterbrook earned a BFA in ceramics from Syracuse University and finished an internship at Anderson Ranch Arts Center in Snowmass, Colorado. To see more of her work, check out www.rutheasterbrook.com.

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