Testing Plainsman Clays

Recently I arranged for my wife and myself and a fellow potter and colleague to sit for Japanese tea ceremony at the local tea master’s home, here in Lafayette Colorado. ┬áHiroko Akima’s tea bowls are all from Japan, and turning them over and examining the feet is part of the ceremony, something that potters everywhere love to do. I was immediately struck by the beauty of what I realized were indigenous Japanese clays, dug and used locally, and I realized that American potters are missing something that could solidify and strengthen our identity, by gaining the insight in the use of a native clay body to help teach us who we are as potters and individuals.

When I pulled out my box of test bars I realized that the native clays used by a manufacturer in Alberta Canada, Plainsman Clays Limited, were among the best I had ever tested. By “best” I mean low shrinkage, excellent plasticity, absence of warping and cracking, and variety of color and texture. This last quality of color and texture refer in particular to a blended high-iron Plainsman product known as Firered clay, which includes a maroon clay from my home state of Montana, and which burns black at cone 10 in reduction. My colleague, Sharon Morris, uses a dark firing commercial stoneware body from Laguna, and encouraged me to seek out the making of a black stoneware body.

My method of originating a claybody, gained form Jim Robinson’s 1988 Studio Potter article, “Body Building for Potters”, is first to find a “suite” of clays for us in a clay body, and after the process of sending for samples from Canada, I made a line blend between Firered clay on one side, and an equal parts combination of Plainsman Fire Clay, Palestone, Plasticfire, and Helmer kaolin on the other, including a small percentage of Kaosand for texture. Needless to say I can’t wait to see the fired results! Due to the geology close to home, finding a native stoneware clay in Colorado might be impossibly difficult, and when commercially available and finely ground native clays are available both domestically and internationally, the choice for me is obvious. Also, as I made a line blend between Plainsman’s native stoneware clay, Palestone, and Firered, I noticed an immediate drop in workability in comparison to a combination of the Plainsman clays mentioned above and Firered. My teacher and mentor, Jim McKinnell, always included a wide variety of individual clays in his clay body compositions, and always talked up the need for wide “particle distribution,” for maximum workability and for longevity of the composition, as individual clays become unavailable. Now I understand what he was talking about.

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