Costume pins may be made of clay. If more than one is to be produced, the form is first modeled in water clay or a commercial oil clay. The design should be compact and must not have undercutting parts. It should be no thicker than 1/2 inch. Smooth the forms with water if wet clay is used. The model should be made on a piece of glass or some other slick surface. Make a wall of clay high enough to keep the plaster from running over the base.
Mix a small bowlful of plaster of Paris. Use petroleum jelly, lard, or water glass to keep the plaster from adhering to the base. When it begins to get creamy, pour a thin layer over the model. Blow on the plaster to remove air bubbles that may have formed between the clay and the plaster. Cover the model with enough plaster to make the mold 2 inches thick.
PLATE XLVII. Pour the mold full to a level with the top as shown.
PLATE XLVIII. Press the clay into the mold.
When the plaster has set, remove the mold from the base and pull out the clay. It may be necessary to scrape the edge of the mold if plaster has crept under the model.
PLATE XLIX. Cut the excess clay from the impression.
To make a pin, fill the dry mold with more than enough clay, Plate XLVIII. Pack it in carefully. With the extending clay, pull out the impression. In Plate XLIX, the excess clay is cut off with a knife. If the clay is rough, it may be smoothed with the fingers and some water.
Dry, fire, and glaze the pin. Costume pin fasteners are cemented in place after the pin has been glazed. Use transparent cellulose glue. If a safety pin is to be used, a groove should be cut in the moist clay. The pin is cemented in place after the glaze firing. It may be necessary to glue a piece of cloth across the back of the costume pin to hold the safety pin more securely.