How to Incorporate Colored Clay into Delicate Pinched Coil Vases Cheryl Malone

With their delicate undulating rims, Cheryl Malone’s seemingly paper-thin vases bear a striking resemblance to flower petals. No surprise since Cheryl is inspired by the growth patterns of plants and their similarities to the coil building process.  

To pull off such petal thin work through the coil/pinch process takes practice, and in an excerpt from our new release Handbuilding Techniques, Cheryl shares her secrets to making it happen. - Jennifer Poellot Harnetty, editor

Deliberate Forming

The working process begins by continuously rotating and pinching while opening out a wedged 200-gram porcelain ball that fits into your palm. Be sure that the base remains thick enough to anchor the pinched form (figure 1). After pressing the pinched pot down on to a banding wheel, use a metal kidney rib to open out the form further and smooth the outside (figure 2). Additional coils are added and simultaneously pinched and folded onto the inside surface of the vessel (figure 3). Using the left hand to pinch the coil up and the right hand to fold it down, attach the coil to the exterior wall surface (figure 4).

The wall surfaces are again smoothed and the vessel is pinched upwards with the thumb and forefinger using both hands simultaneously until the vessel gains height (figure 5) and the coil becomes integrated (figure 6). My intention here is to achieve an even wall thickness throughout the form and to unify the coils making up the piece. Again, use the metal kidney rib to smooth out the form. The more the walls are stretched and smoothed, the more translucent the final vessel will be. Each coiled layer should dry sufficiently (not quite to leather hard) but still be slightly plastic before the next coiling cycle begins. This allows the vessel to be strong enough to hold each successive layer. I often work on two or more pieces simultaneously (figure 7). I choose to work on a form from my Petal Sequence Vessel series while also working on one from the Foliated Vessel series. Although each series is quite different, an interesting dialog and subtle resonance evolves between the vessels by working in this way, which would otherwise not occur.

Incorporating Colored Layers

The stratified colored layers (figures 7 and 8), are made visible by wedging dry measures of oxides (or commercial body stains) into the porcelain clay body prior to coiling. The color of the green band is achieved by adding a quarter teaspoon of chrome oxide and half a teaspoon of tin oxide to 400 grams of porcelain body. Wearing gloves and a mask, the two are wedged until fully integrated and plastic (makes about 4–5 coils). For the rim, 1/8 teaspoon of black iron oxide is wedged into 200 grams of porcelain body (makes 3 coils) The colored coils are added to the vessel and incorporated just like the previous porcelain coils were added. Keeping layers visible and separate takes practice and patience (figure 9).

To remove unwanted smudges or fingerprints of colored clay from the white areas of the vessel, use a sharp metal kidney rib to scrape the colored clay off of the surface, then use the same rib or a rubber rib to smooth the surface. After the last coil is added, smooth the rim to remove any sharp areas but leave the contour so it remains naturally undulating.

Finishing

With the building process complete, the pieces are left to completely dry. I then bisque fire the pieces to 1832°F (1000°C) in an electric kiln, after which the vessels are lightly sanded with silicon carbide sandpaper or fine sandpaper, to remove any roughness to make them ready for decorating and glazing.