Using Colored Clay and Etching Techniques to Explore Patterns and Textures on Functional Pottery

Debra Oliva’s work is inspired by a Samurai warrior’s suit of armor, which she saw on a visit to a museum. Impressed by the combinations of grays, blacks, and browns, as well as the patterns, textures, and fine details, Debra knew she had to work these elements into her clay work.

She does this by throwing in sections with different colored clays, painstakingly etching surface designs, and adding more color with underglazes and terra sig. In today’s post, an excerpt from the Ceramics Monthly archives, Debra explains her process. – Jennifer Poellot Harnetty, editor.


During a visit to a museum I discovered a Samurai warrior’s suit of armor. It was an amazing combination of woven fabrics, leather, and metal. I was taken by the subtle combinations of grays, blacks, and browns, and the relationships between the many patterns and textures, the fine details, and impeccable craftsmanship. This garment presented a clarifying moment that helped me identify the aesthetic I would follow, the elements that are important to me, and where I might look for inspiration.

1 Each color section is thrown separately. While still attached to the bat, the next section is inverted and placed on the previous section rim to rim and then cut free from the bat.

2 The sections are sealed together by throwing downward from the upper section toward the lower section without disturbing the seam.

3 After all the sections are added, final throwing and refining of the form is completed. The base of the work is trimmed in the upright position. Later it will be inverted to trim the foot.

 

Fabrication

When developing new forms, I consider the proportions of the color sections and the placement of decorative elements. Next, I make a rough drawing as a guide and go to the wheel to make a few prototypes to work out the form and get comfortable making the piece. Estimating the amount of clay I will need, I throw the bottom section and finish it with a level rim. I take a measurement of the rim diameter and set it aside while I throw the next section.

I begin the etching process at the leather-hard stage, working on a small section while keeping the rest of the piece damp and covered. My etching tools include a pin tool, pencils, scoring tools, drill bits, and serrated ribs that I cut into small pieces and insert into X-Acto blade handles (4).

4 Lines are incised using a pin tool and solid areas are etched with a tool made from pieces of serrated ribs inserted into X-Acto blade handles.

For the line work, I begin by dividing the space, making a small mark where a line will be drawn. With the piece spinning slowly on the wheel, I incise horizontal lines using a pin tool. Then I incise vertical and diagonal lines by eye. If there are elements to transfer, I use a sharp pencil and a light touch, to transfer designs from tracing paper to the leather-hard ware. I then retrace the patterns to incise them more deeply into the surface. To etch pattern areas, I use my home-made tools.

Firing and Finishing After bisque firing, I lightly sand the piece with fine grit sandpaper to remove any burrs that may still be remaining from the etching process and the dust is wiped off. I brush terra sigillata or commercial underglaze into the incised lines or areas and sponge the excess away (5). I glaze the interior with a black or clear glaze and fire the work to cone 8 in an electric kiln. After the glaze firing, I apply a durable, food-safe wax product to the unglazed exterior and buff it to a soft sheen with a shoe shine brush.

5 After bisque firing, terra sigillata or underglaze is painted over the incised areas and the excess is sponged away.

Working with clays colored with varying amounts of oxides and stains can be challenging as the color sections dry and flux differently. This may create tension between the sections, which could result in warped rims, often only becoming apparent after the final firing. These pieces are unacceptable to me; however, because of this uncertainty and inevitable loss, successful pieces are that much more rewarding.

Check out Curt Benzle’s video clip Tips and Techniques for Making your Own Colored Clay for a way to mix your own colored clays using one clay body as a base, to avoid loss due to different shrinkage rates between the clays.


**First published in 2012
Comments
  • Barbara M.

    I’d love to try your exciting technique! One question before I start: What is the brand name of the durable, food-safe wax product that you use? I have been trying to find such a product for a long time. Thanks for your help and for sharing your technique with us.

  • Karen M.

    Thanks for sharing the process! I bought one of your bowls at Clay3 and still marvel at the craftsmanship, creativity and beauty.

  • Antware P.

    How and when are the different color pieces joined together? Are they joined first and then trimmed to reveal clean lines? or do you carve and separate them first? Is there a percentage of coloring oxide not to exceed as not to affect the compatibility of different sections? I think I have another half a dozen questions or so. There is just not enough info for me to even attempt to experiment.

  • Beth T.

    I’m also interested in information on the wax you use. Wonderful work, and thanks for sharing!

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