The coil bowls in Plate XXX were constructed without the use of a potters wheel. The coils may or may not be smoothed. The round coils make an interesting form for small bowls and jars. They are simple for young children to construct.
PLATE XXIX. The designs are made by the contrasting of dull and polished areas.
A slab of plaster is a good base on which to build small pieces of pottery and little figures. A board may also be used. A number of plaster slabs can be made easily. Each member of the art class should bring a medium-sized pie tin from home for the mold. Grease the pan with vaseline or lard.
PLATE XXX. Coil bowls made without the aid of a wheel.
PLATE XXXI. Dry particles stay on top.
PLATE XXXII. Pour the plaster into the pie tin.
Note: Plaster of Paris is known as molding plaster. It is not to be confused with the kind of plaster used for walls. Molding plaster can be purchased at a lumberyard for about $1.50 a hundred pounds. It should be fresh. Dental plaster purchased at a drugstore is much more expensive and is a finer quality than necessary to use.
Spread several thicknesses of newspaper on the floor and table before mixing the plaster of Paris. Remove all jewelry. Into a bowl half filled with water, sift fresh molding plaster, handful by handful. Plate XXXI. When the water has taken up as much of the plaster as it can and dry particles stay on top of the surface, allow the mixture to stand for two minutes.
With the hand or a spoon stir the plaster until it becomes creamy but not hard like fudge candy. Plate XXXII. Pour it into the form. Tap the pie pan gently at the side so that the air bubbles will rise to the surface. A crockful of plaster should fill several pans.
DO not rinse the hands or the crock having plaster in it into the sink. The plaster will set inside the drain and clog the pipes. Wait until the plaster has hardened and crackle it off the hands. Add water to the bowl after the excess plaster has set and crackle it off the hands onto a newspaper. Add water to the bowl after the excess plaster has set and it will crack out easily. Wrap the scraps of plaster in the newspaper used for covering the table and burn it.
PLATE XXXIII. The tools for making a coil bowl are simple.
Besides a plaster slab or a board for the base of the coil bowl, the potter will need a few other simple supplies. Plate XXXIII. A small face-cream jar with a lid for storing the slip; an old water-color brush for painting the slip on the clay before adding new coils; a piece of outing flannel or an old cloth which can be dampened and used for covering the unfinished pottery; a square of waterproof cloth, shower-curtain material, an old raincoat, rubber sheeting, or oilcloth, for keeping the unfinished bowl damp; a potters knife or a paring knife for cutting the coils; and a low, wide-mouthed jar for water. Often a gallon tin can is used to cover the slab and the pottery between working periods. In that case, a waterproof cloth is not necessary.
Decide upon the shape of the jar or bowl to be made. Some use a pattern cut out of tin or cardboard, called a templet, for guiding the shape of the piece. If the craftsman has a shape well in mind, a pattern is not necessary. The form should be simple. An S curve is not a good shape, and the form should not change too suddenly from a rounded to a straight side.
Dampen the slab of plaster so that the clay will adhere to it and yet not be dried out. Press a ball of clay upon the slab and flatten it. The bottom of the bowl should be 1/2 inch thick. With a tin can or a cookie cutter, cut a round base for the bowl. On a smooth metal-covered board or another plaster slab, roll out a coil of clay. The clay should be rolled with the fingers (see Plate XXXIV) rather than the palm of the hand. If it tends to flatten on one side, pat it until it becomes round. It may take some time to master the skill of rolling round and even coils.
PLATE XXXIV. Roll the coil with the fingers.
Plate XXXV: Apply a coating of slipóclay mixed to a creamy consistency with wateróto the clay base and lay the first coil in place.
Plate XXXVI: Cut the ends of the coil at an angle and add slip to the joint. The coils of the bowl may or may not be smoothed together. If they are smoothed, the walls are supported with the fingers while the thumb is used to slip some of the clay from the upper coil across the space to the lower coil. The fingers are kept inside the bowl when the outside is being smoothed and outside when the inside is being smoothed.
PLATE XXXV. Apply slip to the base for the first coil.
A series of concentric coils may be placed one on top of the other or in a continuous spiral coil. If the coils are not to be smoothed, it requires more and thicker slip to hold them in place. The coils are placed one on top of the other for vertical sides. In building different shapes, place a coil to the outside of the preceding coil for an outward curve of the wall or to the inside for an inward curve. It may be necessary to allow the piece to dry a little before adding other coils after three or four have been set in place.
PLATE XXXVI. Cut the ends of the coil at an angle.
If the work cannot be finished, the piece should be covered with a damp cloth and a waterproof cloth and placed inside a cupboard or a gallon tin can so that it will not dry out. If the clay becomes too dry between working periods, it will very likely crack in the drying or firing if other coils are added. It is the problem of the potter to plan his work so that the piece will be finished before the base is too dry and so that the piece will dry at an even and gradual rate. It may be necessary to dampen the plaster slab if the work is progressing slowly.
The finished piece should be left uncovered inside a gallon tin can or covered only with a waterproof cloth to retard the drying. After a few days it can be taken out, removed from the plaster slab, and turned upside down. Carve a monogram in the bottom of the base. Place a dry cloth over the bowl, and when the clay looks dry it may be left uncovered until completely dry. As long as the clay feels cool to the cheek it is too damp to be fired.