With a kick wheel having a removable head the mandrel can be screwed on and the block turned
down in an upright position. The difficulty of steadying the tool renders this method somewhat unsuitable for this process, where perfect symmetry and a high finish are required. The plaster should not be so dense for turning on the wheel or the kicking is apt to become very arduous and this tends to dislocate the set of the spindle. One of the best of ways is to draw a quantity of shapes, cast their blocks, and turn them on a hired lathe, preferably run by power.
Fig. 12
The finished shape is now well lathered with parting or stopping. This is made by boiling 1 lb. soft soap, 1⁄4 lb. Russian tallow, and a small piece of soda. Another stopping is made by dissolving 1 lb. soft soap in 1 qt. water and stirring in 1⁄4 pt. paraffin oil. Several coatings may be necessary to impart
a waxy surface. When no longer absorbent, it is dried and slightly polished with a bit of cotton waste. At the finish the form should be clean, smooth, glossy, and non-absorbent.
With simple shapes, as in Figs. 7 and 8, a one-piece or a two-piece mould can be made, and here the bottom waste is not necessary, but with any return or foot a three-piece mould will be required. The waxed shape is now divided perpendicularly exactly in half, by a pencil line. (A, Fig. 13.) It is then laid on its side and bedded in clay up to the pencil lines, the clay being sloped slightly down from the marks. (F, Fig. 13.) Box in now with well-soaped boards tight against top and bottom but allowing about 11⁄2” at sides. Wipe the shape over with waste dipped in olive oil but leave no surplus oil on the surface. Plaster well mixed as before is poured in until about 11⁄2” to 2” above the greatest projection of the shape, great care being taken to avoid or dislodge air bubbles. (B, Fig. 13.)
When the plaster is set but still warm, the shape is removed and the side of the plaster that rested on the clay trimmed flat and several joggles or natches are made. (C, Fig. 13.) The shape is now replaced exactly as cast and the new surfaces treated with parting and the whole slightly filmed with oil as before. Great care must be used, for any oil on the actual surface of the mould spoils the suction of the
plaster at that spot. Box in and then cast just as before. This gives two halves with waste top and bottom.
