DIY Network

Trimming the Base Trimming the Base From "Throwing Clay" episode DTHC-102

Master Potter Bill Van Gilder is demonstrating the process of making an oval baking dish. Next up: trimming the base.

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He started with 2-1/2 pounds of clay on the wheel, where he threw a thick base and pulled a wall 3-1/2" tall. Next, he rolled the rim and added decorative lines on the interior and exterior of the bowl. After letting the bowl dry to a soft, leather-hard consistency, he cut a clay crescent out of the bottom of the dish and gently squeezed the dish, coaxing it from a round shape to an oval. He filled the seam with a clay coil and sealed it tightly with a wallpaper seaming tool. Finally, he added textured handles, and the bowl was set aside to dry again to a soft, leather-hard consistency. Now it's time to trim the base and remove any sharp edges (figure A).

1. Turn an inch-high clay pad, larger than the diameter of the bowl, on the wheel head and dry it with a scraper.

2. The handles of the bowl sit above the rim and can be damaged if placed directly on any surface. To protect them, trim away both sides of the pad before centering the bowl upside down on the pad (figure B), leaving the handles suspended over the wheel head (figure C).

Figure A

Figure B

Figure C

3. Using a slow wheel speed, trim the bottom of the bowl, letting the tool float over the surface to create a bevel (figure D). Trim both the sides and the "top" edge of the base, creating a bevel slightly less than 1" wide. Next, using first a damp sponge and then a rubber rib, burnish the surface and stamp your potter's seal into the lower portion of the dish (figure E).

Figure D

Figure E

4. Place the dish on a clean surface to air-dry until it is bone dry.

5. When the bowl is completely dry, load it into an electric kiln (figure F) to be bisque-fired at a temperature of 1,750 degrees. After firing for 10 to 12 hours, the kiln must cool for at least 24 hours before being unloaded.

6. Apply wax-resistant emulsion to any part of the bowl that needs to resist the glaze. If a bowl has glaze on the bottom, it will stick to the kiln shelf during firing. Elevate the bowl on a clay cylinder placed on a band wheel (figure G); elevating the bowl makes the application of wax-resistant emulsion an easier process. Next, apply the emulsion to the bowl base (figure H) and along the bevel, which is a little less than 1/2" up the side of the pot, and let it dry, a process that should take three to four minutes.

Figure F

Figure G

Figure H

Figure I

7. As the emulsion dries, Bill tests black, amber and cream rust glazes on clay tiles. To ensure the colors are true, he made the tiles of the same clay as the baking dish. By themselves, the glaze colors are unassuming, but when the cream rust glaze is dipped over the black and amber colors, the shading becomes unusual and unique (figure I).

RESOURCES :

Kilns
L & L Kilns
Website: www.hotkilns.com

Clay
Highwater Clays
Website: www.highwaterclays.com

Extruders
American Art Clay Co. Inc. (AMACO)
Website: www.amaco.com