Glaze mixing and testing is really complicated and can involve a lot of testing and time and effort, but not everyone has the interest or inclination to delve into the complexities of chemical and mathematical formulation.
Luckily, some of the folks who really get into this kind of thing have jobs testing and making glazes—and then they make those glazes available for purchase. Some folks use commercial glazes exclusively, and a lot of educational institutions count on them for convenience and reliability. In this feature, Lisa Bare Culp explains how she discovered the advantages of exploring commercial glazes, and how some of her previous attitudes changed in the process. Plus she shares a couple of projects. – Jennifer Poellot Harnetty, editor.
As a potter and instructor for many years, I’ve always mixed my own glazes, or relied on other professionals who mix dry glazes to my speciﬁcations. Recently, an idea for a single pot challenged me to experiment with commercially-made glazes. The outcome has been successful with vibrant new color selections, time savings and the convenience of readily available glazes screened for toxicity—all this without compromising my workspace or my standards.
What changed my thinking on commercially prepared glazes was my desire to introduce bold new colors into my work. I envisioned a piece with contrasting matt black-and-white slip surfaces offset against a single area glazed in vibrant red. My local supplier recommended a food-safe, nontoxic red glaze, Mayco’s Stroke & Coat Cone 06.
Early tests resulted in pieces with dramatic and beautiful contrasts between my porcelain slips and the red glaze. In one test, I used Stroke & Coat SC-73 Candy Apple Red, to highlight areas of bisqueware. In another, I used SC-74 Hot Tamale. Sometimes I applied the glaze with a big brush in a single, expressive stroke. Other times, I squeezed the colors from a slip trailer and a turkey baster.
After these loose applications, I dipped the entire piece in my usual cone 6 glazes. Because of their gum content, the commercial glazes resisted my glazes slightly, making the bold strokes of color come through vividly. Stroke edges were blended and their colors softly striking against the cone 6 palette. The outcome was as satisfying technically as it was aesthetically; I was satisﬁed with the melt (Stroke & Coat is a glaze, not an underglaze), the color and the absence of pinholing or other major ﬂaws at cone 6.
A New Tool
Further experiments with sgrafﬁto, layering, mixing with slip and stoneware glazes, and multiple ﬁrings have opened up commercial glazes as a new artistic tool—albeit an unexpected one—to share with students. They have learned the importance of experimenting with new surfaces, new materials, combining techniques and achieving balance with different kinds of material.
If you’d like to experiment with commercially prepared glazes, I’ve included three of my projects for you to try. Mixing my own recipes will always be an important part of understanding the science behind the art of pottery making. But successfully integrating commercial glazes in the mix is just one more way to pursue the function and beauty of ceramics.
Squeeze a large amount of Stroke & Coat SC-73 Candy Apple Red across the interior of a bisque-ﬁred bowl. Use a 2-inch brush to apply a thin coat of Mayco’s Elements Chunkies EL 203 Coal Dust (this is a low-ﬁre effect glaze with crystals) over the Candy Apple Red. A nice feathered edge is created when the piece is dipped into a cone 6 black glossy glaze.
Apply a thick coat of Mayco Stroke & Coat SC-71 Purple-Licious and SC-74 Hot Tamale with a large brush to the interior surface of a leather-hard bowl. Once the colors are slightly dry, the design is carved through the glaze with a loop tool, then bisque ﬁred to cone 08. Dip the entire piece twice in a cone 6 matt white glaze and ﬁre to cone 6 in oxidation. The commercial colors show well through the white matt.
Note: If the carved lines are too ﬁne they may ﬁll in when the glaze melts.
On a heavily textured, bisque-ﬁred piece, apply a cone 6 porcelain black slip as a stain, wiping off the high spots with a damp sponge.
Use a 2-inch brush to apply Stroke & Coat SC-71 Purple-Licious to the high spots with a dry brush technique. Next, dry brush Mayco’s Stroke & Coat Red SC-74 Hot Tamale and SC-27 Sour Apple onto the interior. Apply a thick coat of the red glaze in isolated areas to obtain a bright color.
Apply wax resist to the interior surface of the piece and allow to dry. Dip the entire piece in a cone 6 blue glaze.