| Firing and Glazing the Mugs |
| Firing and Glazing the Mugs |
From "Throwing Clay"
episode DTHC-104 |
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Master potter Bill Van Gilder is making a set of decorative mugs, which are now ready to be fired and glazed.
Bill started each mug from a one-pound ball of clay and threw a basic cylinder. He pulled the walls a uniform 1/4" thick and beveled the rim, smoothing it with a sponge to make a smooth surface from which to drink. When the mugs were leather hard, he inverted one on a clay chuck and trimmed a beveled edge. Next, he pulled the handle blanks from a wet piece of clay, using his thumb to pull decorative grooves down the length of the handle (figure A).He attached the handle blanks to the top of the mugs, dipped the lower portion of the handles in water and stretched them until the handles were approximately 5" long. With a small piece of wooden dowel, he secured the handles to the bottom of the mugs. A slight upward lift with a wet finger gives each handle its final shape, and the mug is set aside to dry for 48 hours, letting it become bone dry (figure B).
1. Before loading the mugs into the bisque kiln, Bill checks for any surface roughness on the rims, the part of the mug that touches the lip. He puts on a dust mask to prevent breathing in clay dust particles and rubs the rims very lightly with a synthetic green kitchen scrubbing pad (figure C).2. He loads the group of mugs into the kiln, where they will fire at 1,750 degrees for 10 to 12 hours, then cool in the kiln for at least 24 hours before being unloaded (figure D).
3. Once cool, the mugs are ready to be glazed with two different patterns, using a technique called wax resist (figure E). The first pattern is simple (figure F), the second style more decorative (figure G).
4. Bill uses green and black glazes; where the green glaze is overlaps the black glaze, it produces a shade of blue.5. First, he applies wax to the base of the mugs. He places the mugs on a banding wheel and, using a narrow foam brush, applies wax-resist emulsion to create a neat, even wax line. He works the wax into every nook and cranny on the base of the mug, then lets it dry; drying takes about five minutes (figure H). 6. While the wax is drying, Bill mixes the glazes. He will dip the mug in the glaze, let it dry, apply wax-resist emulsion on the top portion of the mug, then redip the mug in the green glaze. At this point, the wax resist really starts to come to life. 7. Holding the mug at the rim, he dips it in the glaze for three seconds, then lifts if out and sets it aside to dry for approximately 30 seconds (figure I). Any glaze drops that might be on the wax resist on the bottom of the mugs are wiped off with a damp sponge; if the glaze drops stayed on the mug bottoms, the mug would fuse to the bottom of the kiln shelf during the high-temperature firing. Bill is careful to clean, or "fettle," each of the newly glazed mugs (figure J).
8. While Bill is decorating the mugs, a second wax-resist technique enhances his creative side. The wax on the bottom of the mugs is water based; the second wax technique uses oil-based wax. Bill does a simple decoration for the first mug. Using a variety of brushes, he draws a repeating series of thin lines (figure K). For the second mug, he draws a more complicated pattern of repeating stems and leaves. Using his fingertip, he adds dots of glue for added interest (figure L).9. He quickly dips the mugs in the green glaze and sets them aside to dry for 30 seconds before putting them in the kiln for a high-temperature firing (figure M).
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
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