The mold is now set upside down to drain. It should not be placed upon the table but upon two sticks laid parallel so that the drip may hang clear. Several molds may be filled in this way at one time and after about twenty minutes the one first filled may be opened. The bottom is gently detached and the upper part of the mold, consisting of two halves, is laid upon the table on its side. A little gentle manipulation will now suffice to lift the one half and the vase will be seen lying in the other half as in a cradle. The clay is still very soft and must be treated carefully. The half mold, with the contained vase, is taken in the left hand and held nearly upright, the fingers below, the thumb on the top. Now set the fingers of the right hand under the bottom of the vase, rest the thumb lightly against the side and tilt the half mold gently forward. If mold and clay are in good condition the vase will fall forward to be supported on the fingers of the right hand and steadied by the thumb. The half mold is now laid down and the vase taken in both hands, set gently on a plaster bat and put aside to dry. It often happens that the vase leaves the mold with reluctance. If the slip be very new, or the mold either damp or hard or worn out there will be some difficulty in effecting a separation. By allowing the work to stand a while, however, and by slightly jarring the mold from time to time with the ball of the thumb the piece can generally be removed without damage.

In using a new mold it is customary to make what is called a "waste filling." The mold is filled with slip and at once emptied. After standing a few minutes it is forcibly opened and the thin layer of clay inside is picked out with a ball of plastic clay pressed against it. A tool should never be used as this will damage the face of the mold. If the clay should stick obstinately a soft cloth used over the finger will remove it. The reason for this waste filling is that it removes the scum which occurs on all new molds.

Cast ware should not be touched until quite dry and then the spare at the neck is carefully cut off, the seams scraped down and the whole surface smoothed with fine sand paper and a soft cloth. Worn out linen serves excellently for this purpose.

Cups and bowls, if molded, are made without spare at the top. In this case great care must be taken to see that the edge is left clean and smooth in the casting. The spare neck on a vase acts as a margin of safety, as it is completely cut away in the finishing. If a piece has no spare the edge must be left without blemish at the first.

CHAPTER XIV
Tiles

There are two methods of making tiles, the dust-pressed method and the plastic. The former is the more usual commercial plan but the appliances for preparing the dust and the heavy presses necessary are not adapted to studio work. The dust-pressed tile is, moreover, somewhat mechanical in surface. It is not suitable for modeling or for any treatment but those of glaze and color. The plastic tile, on the other hand, may be treated by plastic methods and the surface offers a texture which appeals strongly to the artist.

For the successful production of tile a special body is necessary. Ordinary pottery clay is too close in grain and straight tile cannot be made from it. Small square pieces, however, such as tesseræ, can be made from any clay.

It is presumed that a pure white tile body is not required. For studio work the most pleasing white surface is found in an opaque enamel, but for the most part the craftsman will wish to work for colored tile. A cream or buff body is all that is necessary, therefore, and the foundation of this is a clay known as sagger clay. In order to secure the necessary porosity a fine "grog" must be used. Grog is burned clay. After working awhile there will be an abundance of this in broken unglazed pottery but at first some soft fire-bricks must be pounded. This is laborious work, but a boy can usually be hired to do it. The brick or broken pottery is crushed in an iron mortar but should not be broken too fine. Two sieves are necessary, one of 20 and one of 40 meshes to the linear inch. The coarse powder which passes through the 20 mesh and lies upon the 40 mesh is used. This is called 20-40 grog. The dust which passes through the 40 mesh may be saved for kiln work. It is useful for setting biscuit pieces one upon another as it will effectually prevent sticking. This powdered grog is also useful in the case of flowing glazes. A thick layer on the bottom of the kiln will catch any drops of glaze and save the kiln from damage.

A quantity of the 20-40 grog having been prepared, a mixture should be made of:—