Published Oct 12, 2022
Slip trailing is a great way to add decoration to pots. Most ceramic artists use a fairly liquid slip when slip trailing. But after watching a baking competition on television, Sharon Romm started experimenting with using thicker slip to decorate pots like a pastry chef would decorate a cake. She shares her results in today's post.- Jennifer Poellot Harnetty, editor
Two options are available at clay supply stores for piping: squeeze bottles and bulb applicators with medical needles of various gauges. I believe that these are more difficult to control than the standard pastry bag and you’re limited to producing lines but no shapes. Pastry bags are made from thin, flexible, tightly woven, plastic-coated canvas. They are reusable and, like an old sweater, become softer and more comfortable with age. An 8-inch bag is easiest to manage, but bags come in sizes up to 2 feet in length. Plastic disposable bags are also available but are stiff and harder to control.
The tip determines the shape of the design. Some tips attach with plastic adapter rings: an inner ring is dropped inside the bag and pushed part way out of the opening. The tip is slipped over the ring, and then an outer ring is placed over the tip and screwed onto the inner ring. This permits changing the tip without emptying the bag. Other tips are designed to be dropped inside the bag and pushed part way out of the small open end. These can’t be changed without emptying the bag first. Stainless steel decorating tips are available with openings of various dimensions to create lines, dots, flowers, leaves, lace, basket weave, stars, ruffles, and shells. Purchase individually or in sets for less than a dollar per tip (figure 2).
I use Cool Ice porcelain, which, when glazed at cone 6, is gorgeous, white, and forgiving. It’s imported from Australia and available from Seattle Pottery Supply (www.SeattlePotterySupply.com). Cool Ice is only minimally more challenging than stoneware (really!) and the smooth, creamy results are almost edible. Save your trimming scraps, then reconstitute with water. Soak until thick and moist, then blend with a hand-held mixer.
To which consistency? You’ll read about “sour cream” or “thick yogurt” or “medium butter cream.” Try different blends to determine your preference. For best results, the slip must extrude smoothly through your piping device. Add bits of clay and mix to thicken, or add water to thin as needed (figure 3). Fold a cuff outward on the bag’s opening. Fill the bag about ¾ full with slip using a spatula. Secure with a stretchy rubber band twisted around the bag’s top to prevent the porcelain from oozing onto your hands. Wilton makes inexpensive, reusable bands that are found on the Internet (figure 4).
Practice Makes Perfect
Start practicing by placing drawings or published designs under a sheet of heavy clear plastic or a piece of Plexiglas. Ready your bag by testing the flow and begin to draw (figure 5). Repeat the exercise by wiping the plastic clean and starting again. Also practice on slabs of clay, which can be cleaned with a rib and reused or fired as test tiles so you can review the results and experiment with glazing options.
Icing on the Pot
Now that you’ve had some practice, it’s time to try your skills on a vessel. If you’re throwing on the wheel, use a six-inch square bat. Leave the piece attached to the bat while you decorate. For the best results, it should be fairly wet. Hold the bat on your lap as you work and repeatedly reposition it to access all surfaces (figure 6). If your piece is too dry, put it back on the wheel and spray it or apply a damp sponge to the surface as it spins. When decorating, keep the design below the lip to avoid later interference when trimming.
Start with one design element then decide where you’d like to place the next. Sometimes carefully planned outlines are better on paper than on clay. Do things by eye. Don’t measure if you can help it. Exact measurements will drive you crazy.
After decorating, cover the piece with a bowl or bucket to avoid marring the design. To properly adhere, the wet slip must equalize in moisture content with the wet clay body. Resist the temptation to peek for several days. Uncover and allow the piece to become leather hard in the open air.
Work on gently smoothing any rough edges of the design. There’s opportunity at this stage to do minor corrections, too. Shapes can be adjusted and irregularities smoothed using a soft brush dipped in water (figure 7). If a segment of a design element falls off, wet the area, re-pipe the element, and allow the moisture content of the design and the piece to equalize again for a few days.
Clean up the foot while your work is still on the bat then run a wire underneath to release it from the bat, trim the pot if necessary, and allow the piece to dry before bisque firing. If sharp edges remain after the firing, wear a respirator to protect from dust then smooth them using a piece of sandpaper or a bisque file. Wash the piece before glazing to remove any dust particles from the surface.
Refining Your Skills
Attend a cake decorating class at community college or craft/hobby store. Arrange to spend an hour with an independent cake decorating instructor. Make sure he/she has expertise in piping rather than in making flowers or other techniques not easily transferable to clay. Identify a pastry chef or cake decorator and spend time at your local bakery observing them at work.