Earthenware with Intricate Surface Patterning

Kaname Takada’s Double-Walled Bowl (2830), 7½ in. (19 cm) in diameter, earthenware, terra sigillata, slip, glaze, fired to cone 05, 2016.

My work starts with patterns made with slips and glazes. The shape, scale, colors, and textures of my pieces are chosen to complement and enhance the patterns. Double-walled bowls are one of my favorite forms to work with.

Wheel-thrown earthenware platters with slip decoration make up the main body of my work. About 10 years ago, I was ready to try working with a form that was more three dimensional and had more vertical surfaces. I made various forms without changing the clay body or decorating techniques I was using, with mixed results. The bowl was especially difficult to adapt to the decorating techniques I use. I struggled with visually unifying the interior and exterior surfaces. I use my platter rims as borders to frame patterns, but the same solution did not work well with the bowls, because the rims visually divided the interior and exterior surfaces. I also felt that I was making another plate, with slip decorations on the front and back, without taking advantage of the form. Working on the concave interior surface was also difficult and so, on some of them, I used a liner glaze on the interior surfaces.

Around the same time, I was invited to participate in an exhibition at the Johnson-Humrickhouse Museum in Coshocton, Ohio, for which all invited artists were to create work in response to an artifact or a group of artifacts from the museum’s collections. I made a slab-box piece based on the woven pattern of a Native American basket.

1 Each double-walled bowl consists of three parts: an outer bowl or shell, a top plate, and a small inner bowl.

2 Measure the diameter of the inner bowl using calipers.

3 Cut a hole slightly smaller than this measurement into the center of the plate.

The box later evolved into my Masu series of cubes that are based on traditional Japanese wooden measuring cups. I was really pleased with the results. It took me a while, but eventually I realized that they were also cube-shaped, double-walled bowls. This realization gave me a solution to the design problem I was having—integrating pattern on the different surfaces of bowls—and led me to making double-walled bowls on the wheel.

Making double-walled pieces was not new to me. As a college professor teaching ceramics, I have taught my students how to make double-walled pieces in the past. However, we focused more on exploring how to engage the negative space between the inner and outer walls by cutting shapes out of one or both walls. In contrast, I have come to the  double-walled slab-built cubes and wheel-thrown bowls as the way to maximize the exterior surface area for slip and glaze decorations and create flatter surfaces that can be decorated more easily. The size of the inner bowl has become smaller over the years. The flat plane connecting the inner and outer bowls eliminated the issue of rims becoming a border, as pattern could easily continue over this surface.

4 Score, slip, and attach the smaller bowl to the plate, then measure the outside diameter of the larger bowl using calipers, and transfer this measurement to the plate.

5 Score, then add slip to the plate edge where it will come in contact with the outer bowl or shell.

6 Attach the outer shell to the flat plate, then trim it to the desired contour.

The sizes of the double-walled bowls are relatively small. They are small and light enough to be held easily by anyone. I make them by assembling the bowls from three parts: a top plate, an inner bowl, and an outer shell (1). I had experimented throwing all of them together as one piece as well as throwing the inner bowl and top plate together and attaching them to the outer shell but I have come to the conclusion that I have better control shaping the parts if they are thrown individually.

I throw the outer shell first, then the inner bowl, and then the top plate. The top plate is usually thrown a few inches wider than the outer shell. I throw the parts off the hump on Masonite, plastic, or plaster bats depending on the size and shape and how quick I want them to dry.

7 Run a wire tool under the finished form to release it from the bat, then let it sit on the bat to reach leather hard.

8 When trapped air makes the form puff out a bit and makes the edge of the flat plate start to lift up, remove the piece from the bat.

9 Use an X-Acto knife to release and remove the center disc of clay covering the inner bowl.

10 Use trimming tools to remove excess clay from the transition between the bowl and the edge of the top plate.

The double-walled bowls are assembled upside down when the parts reach the leather-hard stage. The center opening is cut into the top plate first and the inner bowl is attached to it and then trimmed (2, 3). I have not had any issues with cracking in the seam between the inner bowl and the top plate. Next, the outer shell is attached and trimmed (4–7). This attachment to the top plate needs to be thoroughly secure as pressure from trapped air stresses the join.

As it dries and contracts in size, the trapped air inside makes the shape puffy and raises the edge of the bowl for easy release from the bat (8). After being removed from the bat, the assembled bowl is further trimmed and cleaned right side up, including removing the center disc of clay covering the small bowl (9, 10). I prefer a slightly convex top plane to a flat one, and achieve it by letting the still-trapped air in the drying bowl to push the top up. A small hole is made to release the air once I am satisfied with the curve of the top. The timing of releasing air is critical. If I wait too long, too much air pressure may cause the joint between outer shell and top plate to break. If I let the air out too soon, sometimes this causes the top to sag.

11 Spray or brush on terra sigillata to start creating the surface layers.

12 Draw lines on the surface of the bowl to divide it into segments.

13 Create geometric patterns between the vertical lines, decreasing the size of the shape as the diameter of the form decreases.

14 Use liquid latex to mask off areas of the pattern before applying more layers of terra sigillata.

On some of the pieces the patterns are drawn with a needle tool when they are leather hard, but most of the surface decoration happens when the pieces are bone dry. Once the bowl becomes bone dry, terra sigillata is applied with an air brush and/or with hake brushes (11). I wait for each layer of terra sigillata to dry and then use a mechanical pencil and rulers to draw patterns directly on the surface (12, 13). Liquid latex is painted on to mask off areas before subsequent layers of terra sigillata are applied (14).

When the application of terra sigillata is done, the latex is removed (15), more lines are penciled in, and dots of colored slips are applied with a slip trailer to add more tactile quality to the surface (16). Though I currently use triangle-based patterns extensively, I have tried a variety of patterns before. The pattern inspiration came from various sources, but I have been influenced by traditional and contemporary American quilts and traditional Japanese patterns the most.

15 Peel off the liquid latex after applying the last layer of terra sigillata.

16 Add slip-trailed dots to the surface to add a tactile quality.

17 After bisque firing to cone 08, add more lines to the surface to help define the pattern for applying a clear glaze.

18 Apply the clear glaze in an overlapping manner on the terra sigillata patterns.

 

Double-Walled Bowl (2834), 7½ in. (19 cm) in diameter, fired to cone 05.

On some pieces, I build up layers of dry-brushed slips of different fusibility using various kind of tools and brushes. This creates more textured and tactile surfaces on the otherwise flat and smooth pieces.

After bisque firing to cone 08, more lines are penciled in (17) and clear glaze is applied, first in an overlapping manner on the terra sigillata patterns. Over the years I have experimented with different clear glazes and ways to apply them. I have now settled on painting a commercial clear glaze on the surface using fine brushes without masking (18). Though I used to use liquid latex for glazing as well, I found that painting glazes with brushes doesn’t take much more time than masking areas with liquid latex to create patterns and the results were just fine. Other glazes are applied after the clear glaze. Sometimes I apply wax tinted with food dye to protect a glazed area from being contaminated by other glazes as I work. Pieces are then fired in an electric kiln to cone 05.

My immediate reaction to a beautiful piece is to touch and pick it up. It is an emotional reaction rather than analytical observation. I am happy if any of my pieces, including the double-walled bowls, can evoke the same kind of reaction in the viewer.

the author Kaname Takada is a professor in the divisions of Contemporary Crafts and Fine Arts at the Columbus College of Art and Design. Check out his work at  www.studiotakada.com.

Masu-Series Cube (2459), 10 in. (25 cm) in length, earthenware, terra sigillata, slip, glaze, fired to cone 05, 2012.

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