A Well Wrapped Surface David M Self

Appears in the Mar/Apr 2015 issue of Pottery Making Illustrated.

Glazing is only one of the many ways to create new surfaces on ceramic forms. Many times as potters, I believe we simply put too much emphasis on finding and formulating new glazes or altering current glazes to enhance our work. I know this was a common trap for me as I’ve worked through the years. I’ve combatted this problem by using techniques I’ve learned from other art mediums and applying them to my ceramic pieces. One of my favorite methods is what I refer to as slip transferring.

I derived this method based on a watercolor mono-printing process learned several years ago. The watercolor was applied onto a Plexiglas plate and allowed to dry completely. Wet paper was placed onto the plate and rolled through the press. The moisture from the paper reactivated the watercolor, completing the print-making process. I remember that occasionally, only certain areas of the watercolor would transfer successfully to the paper. The areas that didn’t fully transfer are referred to as ghost images. Though they were imperfect, these random, unplanned elements were what usually appealed to me more than the perfectly transferred compositions from the plate.

When I first began trying to implement new surfaces onto my pots, I tried to find a way to mimic that ghost image effect. Through many trials and attempts, I found a comparable technique using ceramic materials and processes.

The Slip

Take the trimmings and scraps from your clay body (I use a high-temperature white stoneware) and let them completely dry out. Try to collect enough clay to fill half of a large bucket, then add enough water to just cover the clay. Within a few days, the clay is completely saturated, resulting in thick, wet slurry. Add a few drops of sodium silicate to the mixture, then blend the slurry using a paint mixer drill attachment. The result is similar to a casting slip but slightly less viscous. The consistency is much like that of latex house paint. It’s viscous enough to pour off of a brush, but not thin like the consistency of water.

Brush one layer of slip onto the surface of a piece of Manila paper that has been cut to fit the shape and size of a leather-hard form (figure 1). With the proper consistency explained above, the slip will be thick enough to adequately show any details brushed into the surface. If the slip is too thin, there will not be enough differentiation between the surface of the pot and the applied slip surface. The slip is about ¹⁄₃₂–¹⁄ ₁₆ inch thick when brushed onto the paper. I’ve attempted to use this technique on other types of paper, but this is the best I’ve discovered for this process.

After the slip has lost its visual sheen, it’s ready to be applied to the surface of the pot. Before application, marks can be made in the slip to create different designs and patterns on the surface (figure 2). I use multiple tools for this process, including but not limited to wooden clay knives, serrated ribs, and toothed troweling scrapers.

Application

Gently wrap and press the slip-coated paper around the leather-hard clay form (figures 3–4). Using a spray bottle and damp sponge, wet the back side of the paper after it’s placed onto the form (figure 5). A soft rubber rib lightly scraped against/across the paper ensures the slip sticks to the clay (figure 6). The sprayed water allows the slip to release from the paper. Working much like a temporary tattoo—the paper is peeled away with the slip clinging to the pot (figure 7).

Next, use a sandbag made of soft cloth to gently press against any slip that may not be completely adhered to the clay surface (figures 8–9). Slip that isn’t fully adhered has the potential to flake off the pot. The weight of the sandbag applies pressure, but its flexibility means that it won’t warp or alter the shape and form of the piece.

Letting the slip-textured pot sit overnight under plastic allows the clay pot and the slip to reach the same level of moisture content. This makes it easier to handle the piece without the fear of damaging the slipped surface, and provides the perfect condition to add color to the surface.

Adding Color with Underglazes

Apply a base coat of underglaze to the entire exterior surface. Additional underglazes and colors can be blended into the base coat in conjunction with the contours and shape of the form (figure 10). The various colors are blended, as if using a painting or watercolor technique. After drying to the touch, more designs can be brushed, transferred onto the form, or partially wiped off for effect.

Place the decorated pieces back under plastic for one more day, bringing the moisture content of all the materials—the clay, the slip, and the underglaze—to the same level, which allows the overall piece to dry evenly.

Staining and Glazing

Bisque fire the bone-dry pot to cone 04. After it has cooled, spray ceramic stains onto the exterior surface of the form. I often use multiple stains of various earth-tone colors, with each stain being wiped away before the next is applied. A black stain is ultimately the last hue placed on the surface. There will be subtle hints of the previous colors peeking through the texture. Remove the stain from the raised areas of the form with a slightly damp sponge (figure 11). It will stay in the recessed areas of the texture, which emphasizes the multiple surfaces and layers, ultimately making the surface visually pop (figure 12).

Watered-down underglazes can also be applied to the surface. Adding this step can create a light, subtle hint of color but is still thin enough that the stain will clearly pull through after the final firing (figure 13).

After a glaze is poured into the interior of the form, I lightly spray a shino glaze onto the surface. When fired to cone 10 in a medium–heavy reduction atmosphere in a downdraft gas kiln, the final result is a surface that has a satin-matte finish. The final glaze doesn’t overpower the subtlety of the soft underglazed and stained surface (figure 14).

David M. Self is a ceramic artist and teacher living in Wichita, Kansas. He received his MFA in ceramics from Wichita State University and currently teaches ceramics at Friends University and Heights High School, both in Wichita. More of his work can be seen at www.davidselfceramics.weebly.com, and at www.facebook.com/davidselfceramics.

Subscriber Extra Image