A considerable variety of hollow cement work, bowls, and flower pots may be made from very simple plaster of Paris moulds. As is well known, plaster of Paris will harden into any shape to which it is applied. The designer can model in plasticene or clay any shape which does not narrow at the top and from this shape may be made a one piece mould which will later give form to the cement. It is possible to take any well shaped glass or pottery or metal dish and make from it a plaster of Paris mould which will reproduce an indefinite number of cement pieces of the same shape. Take, for instance, the ordinary agate ware wash basin. Such a basin is turned upside down and plaster of Paris, mixed with water to the consistency of soft mud, is spread over the surface. When the plaster is hardened the wash basin is removed. It comes out easily if there are no irregularities and if the surface has been well oiled. The result is a heavy chunk of plaster of Paris containing the impression of the wash basin. Such a plaster mould must be thoroughly dried in a warm place. This drying process usually takes a week or more. When the mould is dry the smooth inner surface is covered with a coat of shellac. Immediately before use the mould must be painted over with linseed oil, then coated with a layer of thin gelatine solution. Into the hollow thus produced a sufficient amount of the moist cement mixture is pressed and smoothed, making a cement lining for the mould. This lining should be made fairly thick, as thick as the cement bowl is intended to be. The inner surface should be carefully smoothed and finished by hand. The mould and its cement lining may then be covered with a wet cloth and left for twenty-four hours. When the mould is inverted and tapped lightly with a mallet, the cement shell will drop out and may be treated as the flower pots are usually treated; that is, set aside and kept moist for a sufficient length of time. Such bowls filled with earth and planted with nasturtiums or the like are exceedingly effective.
A Water Garden for The Birds. Can Be Easily Made of Concrete from a Simple Plaster of Paris Mould
The making of solid cement pieces such as stepping stones and the tops of garden seats is a comparatively simple matter. The moulds are usually made of wood in such a way that the sides may be easily removed. There is, of course, no need of a core, so that the cement mixture is tamped in solidly. A very serviceable stepping stone for gardens is produced in this way. The stepping stone moulds which have been used very successfully in Marble-head are made of iron and fastened together with clamps at the corners. The iron frames are made ten and twelve inches square and two inches high, so that the finished "stone" will be thick and strong. The frames or moulds are assembled on a piece of smooth marble or heavy glass; the slab or glass must be oiled as well as the sides of the frame. The open space is simply filled and tamped hard with the cement mixture. If the mixture is well tamped, the sides of the frame may be removed at once. The stepping stone may be moved by hand in about twenty-four hours if it is kept thoroughly wet. Meanwhile it requires the same wet conditions for a long period, two weeks at least before it is ready to use. These stepping stones set in the grass of the lawn are most effective. The grass grows around the sharp corners and soon gives the desirable irregular shape to the "stone." While the cement is still soft it is possible to impress upon its surface any simple design, thereby adding greatly to the interest of the piece.
Most interesting mosaic tiles are made in the following manner. On a sheet of wax or clay is made the deep beveled lines of any outline picture or design. The sheet of clay should be of the size of the proposed tile. Frames similar to the stepping stone frames or moulds are placed about the wax, and soft plaster of Paris poured into the space thus formed. When the frames and wax are removed, the design will be found transferred to the plaster of Paris.
Such a plaster block bearing a design in outline may be impressed upon a soft tile of cement. But the plaster soons breaks down and wears out, so it is much better to have the plaster of Paris design duplicated in brass or iron. Any first-class foundry will undertake the job, and the resulting die may be used indefinitely. When this die is pressed or hammered down into the soft surface of the cement tile, the lines of the design will be left, either raised or depressed as the case may be. If the lines are raised, it is easy to fill into the spaces of the design the colored cement inlays.
Of course, all this work with cement implies practice if the results are to be satisfactory. The beginner must not be discouraged with early mistakes and failures. It is a great deal better whenever possible to have a teacher who has been trained in the various processes. Yet such work might be taken up by any invalid with fair strength in the arms and with the assistance of some one accustomed to the use of cement for ordinary building purposes. At the workshops in Marblehead there are almost always young women learning to teach cement working. They find positions in hospitals and asylums, or as attendants and teachers for individual invalids. A number of successful workshops have been instituted in various parts of the country. It has been the intention of the management of the Marble-head shop to equip with teachers and supplies workshops that shall be scattered over the country in such a way as to avoid competition. While the market for well made cement articles is perennial and good, it is limited; and no city would be likely to support successfully more than one shop.