11. ASH TRAY-Slab Construction

Materials — piece of gray pottery clay, about the size of half a loaf of bread; small amount of clay slip

Tools   - piece of cloth ½yard square; 3 sticks,¼" x 1" x 8"; several wood tools; brush; knife; plaster bat about 4" x 6"

DESIGN. Pottery with square or flat sides is most easily made by the slab method. This is a means of joining together flat slabs of clay. Slab pot­tery is different in character from that made with coils. The slab method lends itself best to angular forms and shapes based on plane con­struction. One drawback is that the straight edges and flat planes are apt to become too mechanical and often mislead the beginner into making objects that are better suited to metal and wood.

The design of an ash tray based on flat planes depends on the pleasing proportions of the planes to each other, or to put it another way, the relationship of length, height, and depth. For a first problem, you may make a square ash tray, choosing the height you think best. Or you may take a slightly more challenging problem and design an oblong ash tray. In designing the oblong ash tray, start by first drawing a rectan­gle for the bottom. Consider its proportion. Is it too square or too oblong? Then draw the side views. Consider them. Are they too high or too low? For example, in considering the bottom, a proportion of 2 to 3 is more pleasing than 2 to 4.

The function of an object will, of course, largely determine its size and shape. An ash tray should not be too large or too small for its purpose. But function is not the only consideration; there is much latitude for altering the design in rela­tion to its appearance. It is desirable to make a paper model first so that no time is wasted in trying to change a finished clay piece. In fact, it is almost impossible to change the proportion of a slab-constructed piece after it is put to­gether.

PROCESS. Wedge the clay thoroughly (see In­troduction, page 12). Make a large slab about ¼" thick in the same way as you made the tile  (see Project X). Make the slab large enough to include the bottom and sides of the ash tray. It is advisable to draw the pattern for the bottom and sides in actual size on the paper first. In determining the length of the short sides, don't forget to subtract ½" for the thickness of the two joining walls, and in determining the height of the sides, to subtract ¼" for the thickness of the base. Cut out the pieces of the paper pattern and lay them on the clay slab. Trace around them with a pencil or some other pointed tool and cut the clay pieces apart with a knife (Fig­ure 1). If the pieces are too soft and bend when you try to lift them, wait until they become firm enough to hold their shape.

Lay the bottom piece on the plaster bat. Take one of the sides and score the under edge where it is to join the bottom. Score the edge of the bottom and paint both scored edges with slip. Lay the side in place and wedge a small soft coil, about ⅛" in diameter, on the inside where the side touches the base. Weld the outside edge with tool or finger. Now put a second side in place in the same way, but be sure to score the edges where the corners meet (Figure 2). Paint them with slip and weld the inside with a soft coil. Continue with the third and fourth sides in the same way. Check all joints to see that they are sealed (Figure 3). If cracks show, paint in with slip and fill them with fresh clay. When cracks persist, cut into them with a wood tool, paint with slip and fill with fresh clay. If cracks appear all along the edges, it signifies that the joint has not been properly made and it is ad­visable to remove the side and go through the process again of scoring, painting with slip, and welding the inside with new clay.

When the ash tray is finished, it can be deco­rated, then fired once, and glazed (see Introduc­tion, page 14, and Project XV).

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