I have always been drawn to organic shapes and textures. I find that my Tree Bark Bowls meet some inner desire to have a balance between texture, color, and shape.

Balancing Act

In creating a texture on the exterior of my functional thrown forms, many things can go wrong. Because this altering process requires drying and stretching the clay, it occasionally rips along any fissures that form. To avoid mishaps and frustration, I like to balance my intentions with those of the clay itself. I don’t force this design when the clay isn’t working in my favor. Because of this, some bowls end up thicker in certain areas or misshapen. I consider the distorted pieces to be a reminder that there is beauty in imperfection. Oftentimes, the pieces that have the best equipoise are asymmetrical. When creating these textured bowls, I keep my ideas and guidelines soft and pliable, ready to be altered. 

Clay and Slip Choice

Before beginning, think about the shape and colors you want for the final piece. For this piece, I used a dark, groggy clay body. I find that the darker colored clay grounds the piece and adds warmth to the glaze, while a bright-colored slip will create a striking contrast for balance and color variation. A groggy clay body helps provide the strength needed during the stretching. I use a white slip for the interior decoration and a tan slip for the exterior walls, which provides a natural, rustic look to the finished piece.

1 Cover the outside of the cylinder with an even coat of a contrasting slip. 2 Brush a thin layer of sodium silicate onto the exterior and allow it to dry for 15–20 seconds.


To create a finished, fired bowl that is roughly 6 inches in diameter, I use 1 pound 12 ounces of clay. The diameter of the piece may vary depending on how well the bowl stretches. 

Start by throwing a relatively thick and even-walled cylinder that is 4 inches tall and 3½ inches wide. This will provide enough clay for the outer wall to form a cracked pattern later on in the process, while the inner wall continues to stretch. If the cylinder has uneven walls, is too thin, or is too tall, the resulting piece may rip when it is expanded, or be exceedingly narrow. 

Once you create the cylinder, compress the walls with a rubber rib for strength and to clean the surface. Next, evenly cover the outside of the cylinder with a contrasting slip (1), then use the rib to smooth the slip if the brush leaves deep lines. 

This next part requires a little bit of balancing. Over time, I have settled on drying the cylinder on a slowly spinning wheel with a heat gun for 1 minute and 45 seconds. You want to dry the piece until the surface of the slip can be touched without leaving an impression. Once dry, add a thin layer of sodium silicate (2) and dry for 15–20 seconds with the heat gun.


Once the slip on the outer wall is dry to the touch, avoid touching or applying any water on the outside of the piece as this will soften the dried slip and create smeared lines instead of a crisp texture. Place one hand and a damp sponge on the interior of the cylinder, then spin the wheel slowly and apply even, outward pressure (3). Begin to shape the piece gradually by doing several passes on the interior with the wet sponge (4). As you stretch the clay, the fissures will become thin and are prone to tearing. To avoid tearing, compress the rim after a few stretches (5). It also helps to compress and shape the stretching clay by placing a soft rib on the inside of the bowl and applying even outward pressure (6). 

3 Place your hand on the inside and spin the wheel slowly. Using your hands or a sponge, apply even outward pressure. 4 Continue to shape the form from the interior gradually by pressing out over several passes with the wet sponge.5 To avoid tearing the form as you shape it, compress the rim after a few stretches. 6 Compress and shape the stretching clay by placing a soft rib on the inside of the bowl and applying even outward pressure.


Once you have your desired shape and size, remove any extra throwing slip from the inside and apply a white slip. Smooth out the surface of the slip using a soft rib. While slowly spinning the wheel, tap the slip with a wooden tool, spoon, or soft rib to create impressions. If you don’t like your initial design or make a mistake, use a rib or brush to erase the design and start again. I tap using enough pressure to push through the slip and reveal the darker clay underneath (7). I will also drag the tool or do slower taps to create lines or smeared markings. 

Trimming and Chattering

When the piece is leather hard, trim the bottom. After trimming, I use the trimming tool to make a chattering pattern on the surface to blend the rough texture of the outer walls with the bottom of the piece. I use metal pallet strapping, which is just under 1 inch wide, to make my chattering tools. I prefer these tools to be stiff, but with enough give that I can bend them by hand with some force. To create smaller markings, you can use other metals like a dull band-saw blade. 

To make chatter marks, hold the tool like a wand with your pointer finger pressing firmly in the middle of the tool (8). To create the right amount of give during chattering, hold the tool at the end, leaving the top half open and free to move. 

7 Tap the slip with a wooden tool, spoon, or soft rib to create impressions, and reveal clay through the slip. 8 Hold the chattering tool like a wand with your pointer finger pressing firmly in the middle of the tool.

Place the tool at roughly a 135° angle to the piece (past vertical and leaning away from you). Press firmly with your pointer finger while spinning the wheel as fast as it will go. Because of the sharp angle and the amount of applied pressure, the tool should catch or snag the clay instead of trimming or carving off clay. This continuous catching will vibrate the tool and form chatter marks (9). Move the tool up and down the base to blend the wall texture with the trimmed foot. If no chatter marks appear, adjust your pressure or the angle of the tool.

9 This continuous catching will vibrate the tool and form chatter marks on the clay.


Bisque fire your piece when it is fully dry. To further enhance the color and texture contrast, apply a patina or wash to the outer walls of the piece. This will stain the slip and fill the fissures with a darker color. Once added, apply a high-gloss glaze to the interior and fire to the appropriate temperature. The finished pieces remind me of geodes, which have such a contrast behind their rough outer appearance and polished inner beauty. 

Delores J Farmer is a native of Durham, North Carolina, and a graduate of North Carolina Central University, where she studied English and art. She is self taught and has been working as a full-time potter since 2013. She currently runs her own pottery studio, where she teaches classes and workshops, makes her own pieces, and offers assistantships to new pottersTo learn more, visit www.delorespottery.com.