Wall to Wall Decoration Colleen McCall

Appears in the Jul/Aug 2015 issue of Pottery Making Illustrated.

My colorful, hand-painted pottery is decorated from top to bottom, inside and out. Rarely is there a surface left bare or free from pattern or texture. Whether painted, carved, cast, or stamped, I add interest to every angle of my dark brown, stoneware pottery with layers of porcelain slip, a bevy of underglaze colors, and white, breaking tin glaze. Vintage textile prints and cast glassware are my primary inspiration. I like drawing upon the familiar to evoke memory and emotion, but it’s only a touch point for a fresh and unique collaboration.

Initially, I threw round shapes on the wheel and decorated them. The patterns quickly became more interesting, leaving me to seek out new shapes and alternative construction methods to improve the quality of the overall design. After failing to make truly square pots I found a square form to cast in plaster and press mold with better success. I soon began collecting glassware, melamine, and plastic in all shapes and textures to make molds from. The shape of my hexagonal mold is somewhere just between a circle and a square. Being both round and angular, it’s always exciting to explore its many variations of form and surface.

Creating a Plaster Press Mold

For this hexagonal mold I used a thin, non-porous plastic take-out dish, which could be cast as a one-part mold. Prototypes can also be made by combining objects to achieve new shapes. For example, starting with a wide square plate placed face down on the table and stacking an upside-down shallow bowl on top of the plate creates a pasta bowl shape with an ample rim for decoration.

To prepare an object for casting, add wet clay to the object’s inner rim to secure it to the work surface and to prevent the liquid plaster from seeping under the object when it’s poured. Next, with the dish inverted and the clay rim secured to a flat surface, build up short, thick, clay walls around the thin plastic edge of the disposable dish to contain the plaster as it’s poured (1). When creating a one-part mold with a non-porous object, mold soap is generally not necessary. After the prototype is secured, mix the plaster using a ratio of 6 pounds of plaster to 2 quarts of water, adding the plaster to the water. Let the unmixed contents slake undisturbed for at least three minutes to hydrate the plaster, then slowly mix it using a Jiffy mixer or similar for 3 minutes to initiate the chemical setting process. Just as the plaster is beginning to thicken, pour it over the prototype. Pour when liquid to prevent the formation of air bubbles on the surface of the model. As the plaster thickens, but before it sets, you can manipulate it to mound evenly over the form (2). The plaster heats up as it sets.

Once the plaster has cooled fully, remove the clay walls, smooth down any rough edges with a green kitchen scouring pad, and  wipe down the mold with a damp sponge (3). Allow the mold to completely dry before using it.

Prepping the Clay and Filling the Mold

I stack wedge my clay for slab rolling as I find it reduces warping by aligning the clay platelets. Slice a chunk of clay into two thin pieces, press each one flat, then slam one half on top of the other, pressing it flat again. Slice and repeat 6–8 times until the clay feels more fluid. Gradually flatten with a rolling pin, flipping the clay over and turning it 90° with each pass until it reaches its final thickness of ¼ inch. Compress the slab with a metal rib to further align the clay particles.

Use the slab while it’s soft to fill the mold, easing the ribbed surface face down into the interior (4). Gather the edges slightly to help the clay fill the mold without stretching too much. Press the clay against the mold, and add wet clay to backfilling any areas that become thin. It may take a few attempts filling the mold before you figure out the nuances of the form and process. Trim off the excess clay around the rim using a plastic tool (metal tools could chip or gouge the plaster) and use a stiff rubber rib to compress the rim, the clay on the top side of the slab, and to even out and smooth the surface (5).

Variations of Form

For a deeper bowl shape, build short slab walls around the perimeter of the bowl. When doing this, be sure to reinforce any seams with small coils on the interior of the bowl to prevent cracking (6). For a sturdier and more elegant bowl, add a coil or flattened band to the top edge to thicken and define the rim.  The basket bowl has a slight swoop at the rim where a single coil has been attached to the rim with slightly more clay in the corners for extra height.

At this point the bowl is ready for its first coat of porcelain slip. A total of three coats should be applied while the clay is still supported by the mold (7). Wait for the slip to dry between coats.

When the slip-painted clay has firmed up, remove it from the mold by sandwiching a board on top and carefully flipping upside down. While upside down, use gentle but firm pressure to  score and slip on a foot ring or foot nubbins.

To create a basket effect, extract cut outs from the corners of the form with a thin blade after the bowl is removed from the mold. Smooth the edges of the cuts (8). Carving or exterior painting is best done now with the piece firmly inverted (9).

Learning how to Combine Patterns

My pattern book is sorted into five sections to organize the spatial dynamics of a particular pattern. Motifs such as animals or single flowers are the first section. A motif functions as a unit that can either be used alone as a focal point or can be repeated in various ways to create a pattern.

Section two, overall patterns, is most abundant since many fabrics are printed to be used in multiple directions. These patterns are random and don’t adhere to any one orientation. They work well on any shape.

The third section, vertical patterns, is limited in use to upright forms such as vases and mugs or square and rectangular shapes that have a top and a bottom. As an example, wallpaper tends to be vertically oriented.

What I call ground patterns, collected in the fourth section of my book, are those that are more basic and subdued. They act as a filler or create an interesting background when used with a focal point motif.

The fifth and final section contains borders or scrolling patterns that can trim a form or frame an overall design.

When combining patterns I look for similar elements of shape, scale, and line. I can always unify patterns with complimentary color combinations. I also tend to mix styles and historical genres within a piece or in an arrangement of dishware, like bold Art Deco lines softened by an Ikat (a textile dying process) ground with Iznik pomegranates surrounded by calico. I draw each form once and photocopy it multiple times to play with dividing the form into zones for decorating. I can then play with adding patterns together. When I settle on a combination I may draw it once again and copy it multiple times to try color combinations (10).

Transferring Motifs

I use paper stencils to transfer patterns to the form. Occasionally, I enlarge or reduce their scale to fit the form better. If your clay surface is a soft leather hard, I suggest putting a sheet of thin plastic between the clay and the paper template as the moisture from the clay will cause the paper to slough off into your precious line work. Trace the template with light pressure using a dull pencil or ball-tipped sgraffito tool. This leaves an impression of the pattern in the clay that guides your brush work (11).

Handpainting Efficiently

When applying underglazes to create the patterns, I use wax resist thinned with water to paint more efficiently in layers. Apply wax over light areas of color to protect them when painting over with darker colors or to block the edges of motifs to make it easier to quickly fill in a solid background color. The peony and wheat pattern begins with hand painting the stamen and pink petals (12). The brown leaf dots are added with a fine-needled glaze applicator. When dry, the entire peony is brushed with wax resist. I give the wax about 20 minutes to harden before painting the background color (13). Using three coats of color provides a more saturated, solid color. Using a graphite pencil, I then sketch the stem of the wheat in alternating directions throughout the ground. I paint the wheat kernels last in a slightly darker color than the chartreuse. Any time I incorporate a transparent glaze color into the motif, it lessens the painting time but also adds a new dimension to the design.

Sgraffito Tips

My favorite sgraffito tool is a tight cornered ribbon tool. I find it grabs the clay more surely, allowing me to vary the pressure, which alters the line thickness (14). I also keep a variety of sgraffito tools on hand depending on the line quality I prefer. Tip: Depending on the form, you may want to work from left to right if right handed or from the middle out to keep from smudging newly drawn lines. As you begin to carve through the layers of slip, underglaze, and wax, the remains will pile up. Simply dump them out into your glaze and clay recycle bin and continue carving. Don’t brush or blow them off as they may mar the surface and create excess dust. Brush off any straggling bits of clay after the bisque firing when the work is wet sanded.

Wet Sanding Bisqueware

Wet sanding bisqueware removes sharp burrs created by carved sgraffito lines. To wet sand bisqueware, use lots of water to keep the dust to a minimum. I work over a bowl of water with 320-grit wet/dry sandpaper alternating between sanding and sponging to remove dust from the sgraffito crevices (15). Be careful not to sand off the underglaze color. Mistakes can be easily fixed by applying more underglaze to the thoroughly cleaned bisque. Caution: Always wear a dust mask when doing any sanding.

Glazing

The first stage of glazing on the peony and wheat pattern is to apply a transparent celadon green glaze to the leaf and stems of the peonies with either a brush or glaze applicator squeeze bottle (16). Finally, the entire interior is brush coated with two thin layers of transparent clear glaze (17).

Colleen McCall is a full-time studio artist living and working in Elmira, New York. To see more of her work, visit www.colleenmccallceramics.com or visit the Upstate New York Ceramics Invitational at Main Street Arts (www.mainstreetartgallery.com ) in Clifton Springs, New York July 11–August 30.