| Kiln Drying and Glazing the Bowls |
| Kiln Drying and Glazing the Bowls |
From "Throwing Clay"
episode DTHC-101 |
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Master potter Bill Van Gilder has been making batter bowls with spouts and two different kinds of handles. The bowls were thrown on a wheel, and the spouts were formed by hand. When the clay was leather hard, the bottoms were trimmed and the sides smoothed. Loop and lug handles were attached opposite the spouts, and then the bowls were set aside until they were bone dry before being put in the kiln for their first firing (figure A and figure B).
1. Place the pottery in the kiln for a bisque firing. The pots won't stick together because they have not yet been glazed. Firing at a temperature of 1,750 degrees, the tightly packed kiln evenly distributes heat; after firing for 10 to 12 hours, the pottery must cool for 24 hours in the kiln before it can be removed and glazed (figure C).2. Before being glazed, the bowl bottoms are waxed to resist the glaze. If the pots have glaze on the bottom, they will stick to the kiln shelf during firing (figure D).
3. Mix glazes in shades of nutmeg and white. In combination, they make a stark contrast, but by dipping the white over the nutmeg, you can create a soft cream-colored hue.Tip: Bill always tests tiles made from the same clay as the pottery being glazed to see how the glazes vary over surface textures (figure E). 4. The pots are first dipped for three to four seconds in the nutmeg glaze, then dried for five minutes. Where your fingertips held the bowls at the rim, patch the glaze with a fingertip dipped in glaze. Wipe away any excess glaze clinging to the wax to prevent contaminating the next glaze color (figure F). 5. Quickly side-dip the dry, glazed bowl in the white glaze. Dipping quickly is important to prevent glaze build-up, since glaze builds up quickly, and thick layers of glaze could eventually cause chipping as the bowl is used. Also remove excess glaze from any areas of the bowl that have a wax coating (figure G).
6. The glaze is dry when the glossy finish disappears. Then place the bowls back into the kiln for a final, high-temperature firing. The pottery pieces cannot touch during firing; if they do, the glaze will fuse them together. The kiln is heated to 2,200 degrees over a period of 10 to 12 hours and must cool for 24 hours before it is safe to be opened and the bowls removed. At this point the bowls are ready to use and enjoy, both as practical vessels and as objects of art (figure H and 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
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