Published Aug 14, 2023
If you're bored with glazing, working with colored clay is a fun way to get color and pattern onto your pots. In this feature, Faith Rahill walks us step-by-step through the creation of a colored block of clay that she slices and uses as an inlay pattern on a platter.
This colored clay process is often called nerikomi or neriage. This is one of those techniques that is simple and straightforward, but requires a lot of attention to detail. Luckily, Faith covers all the bases for us so that we can plan for success. Enjoy! -Jennifer Poellot Harnetty, editor
Working with Colored Clay
Nerikomi (often referred to as "neriage") is a decorative process established in Japan that involves stacking colored clay and then slicing through the cross section to reveal a pattern, which can then be used as an applied decoration. Nerikomi designs provide a wonderful way to work three dimensionally with patterns and images. The results reflect a combination of both careful planning and accidental surprise, plus it’s exciting work for those who love patterns and are drawn to the wet-clay stage of pottery making. My work with colored clay is slow, exacting and fraught with technical challenges. Along with my love of handbuilding, what keeps me hooked on nerikomi is the pleasure of conceiving a design, followed by the creative challenge of building it in cross section. Slicing through a new block that you’ve been working on for the past hour or two has the same exciting quality of unloading a kiln load of new work.
Colored Clay Preparation
Some clays work better than others when it comes to slicing cleanly and not dragging the color. Find white clay you like at any temperature and add your colorants. When working with stacked colored clays, they must be very wet in order for the clay to blend smoothly without seams or cracks. To make the clay wet enough for this technique, add water to new bags of clay and let them sit for a week or more. The uncolored base clay then needs either “sloppy pugging” or to be worked up with your hands. (My old Bluebird mixer works, but I do have to clean out the de-airing box often.)
Colorants for Colored Clay
Colorants can be added to any white clay. Since I periodically change my mind about the intensities of color, over time percentages can change. Combining two different colors in a test sometimes yields nice results. Ten percent means, for instance, 5 pounds of wet clay mixed with 1/2 pound of dry colorant. The colors in this list are Mason stains. You can also use oxides. Years ago, I bought 5 and 10 pound batches not knowing that it was a lifetime supply. If you choose to fire at lower temperatures, there are more colors available to you, as some colors burn out at higher temperatures. Here’s a list to use as a guideline.
Blending Colored Clay
To add color, create a well in a pre-weighed lump of wet clay and spoon the weighed dry material into the well. Add just enough water to make a paste, then slowly mix it together until well blended and wedged. There are hand cream products out there that can help protect your skin. I recommend buying one and applying it before getting to work. I use Kerodex®, which comes from the pharmacist. Two different clays, such as a brown and a white stoneware, can be used together if they shrink compatibly. With all the colorants and clays available, experimentation is a great way to discover what you like and to create your own colors. It also makes opening the kiln more fun.
The Nerikomi Colored Clay Process
1–2. For this nerikomi design, slice thin slabs of uncolored and black-colored clay blocks using 4 lb. fishing line. Roll the slabs together from both ends to form a double spiral. Work on plastic or a wet canvas surface to keep everything as wet as possible. To create the center of the block, press two of the double spirals together back to back.
3–4. To create the stripes, stack thin, alternating black and white slabs together. Use 2 lb. fishing line to cut the block in half. Cut each half again to create four sections. Tip: The fishing line is difficult to see on the table. Tie one end of the line to a button so that it’s easier to find when you need it.
5–6. Slam the double-spiral square on the table to make it flat on all sides, then place the stripe blocks against it. Squish the block into a square, forcing the corners to meet, then slam the block again to make it a square.
7–8. Wrap a thin slice of green-colored clay around the block to give it a border, then gently slam it once more to create a good bond. Place the block on a clean, wet canvas surface and slice it with 2 lb. fishing line across the bottom. Use mat-board slats as guides.
9. Carefully peel the slice off of the block. I slice all the pieces I’m going to need for the next day, and store them between wet handiwipes or wet pieces of cloth under plastic. The slices need to be soggy wet all the way through in order for them to roll seamlessly into a slab of clay.
10–11. Arrange the slices on a rolled out slab that is sitting on plastic. To keep the clay from sticking to the rolling pin, use a piece of cloth between the pin and the clay. Slats keep the rolling even. You’ll see a print of the design when you remove the cloth. Note: An important part of my routine consists of washing my cloths out at the end of the day and draping them across my studio.
12–13. Once the surface of the slab seems dry enough that the rolling pin won’t drag the color around, roll without the cloth. Wipe the rolling pin off after each pass, otherwise you might have to sand at the bisque stage to clean up stray colored clay. Use a cardboard template to cut the final shape of the plate. After lifting the edge to form the sides, I cover the piece and allow it to dry slowly on a bat (until there’s lots of lovely black mold under it). Slow drying reduces warping and allows the moisture to equalize among all the combined clays so they dry uniformly.
I fire to Cone 10 and use #16 transparent glaze from Laguna, adding silica to reduce crazing. Although I get plenty of seconds using this technique, I love experimentation, and am constantly introducing new clays and other variables.
Safety Tip: Working with colored clay requires extra safety measures. When mixing powdered colorants into wet clay, always use latex or rubber gloves, and wear a respirator.
Faith Rahill received her B.F.A. from the University of Oregon in 1973, and has been a studio potter in Eugene, Oregon, for more than 32 years. To see more of her work, visit www.faithrahillpottery.com.