CHAPTER IX METHODS OF COMBINING MOLDS TO CAST LARGE MONOLITHIC CONCRETE WORK THE use of a number of sand molds combined to mold the concrete cast in one piece, is invaluable with many classes of work, as will be easily noted by referring to the drawing of the lawn vase mold shown in Fig. 7; with work of this class it is essential that they be molded monolithic, as when molded in sections it is a very difficult matter to join these several sections together, but what they may be injured by the wind displacing same, unless laid up with mortar and that is not as strong as a monolithic piece of work. The illustration of the lawn vase or urn in Fig. 7, shows a one-half section of the sand molds combined to produce the design complete and ready for use. The first section, from the bottom, or the rim to the vase is easily made from a clay model pattern; this can be formed with a template and the model for rim is made solid, as the core to form the inside of bowl is made separately, hence the models for the outside of urn or vase do not have to be cut out in center to allow for core. The second section is also made from a clay model, which you can fashion with a wood template; as will be noted the size of the different flasks varies in height; this must be done so as to bring the parting of the different flasks at the point that permits the easy removal of the pattern or model from the sand mold; if this was not done you would have difficulty in removing your patterns from the mold and with the case of clay models would have to spoil the model to remove; with the idea of making the parting at the points where the pattern is easily removed, you can use the same clay model for any number of molds The third section or bowl of the urn can be made from a clay model, or you can use as a pattern an ordinary butter-bowl or chopping bowl of the right size and contour; this section of mold has a parting at the point where the outside edge of stem joins upon the bottom of bowl; hence in using a wood bowl as a pattern it must have a flat surface at the bottom equal to the diameter of the stem, or must project beyond the surface of flask enough so that the next section, containing sand mold of stem, will set down closely to the bowl, so the stem joins with same entirely around the circumference of stem. The fourth and fifth sections of mold can be made with the same pattern, by simply reversing same, as the half round moulding placed in the center of stem is directly in the line of parting of the two sections, so is molded half in one section and half in the other. This permits the easy removal of pattern from the sand mold and saves making an extra pattern. The sixth section is easily made from a clay model, in the form illustrated or in any other form you wish for same, and the shape permits its easy removal from mold. The seventh and eighth sections are molded from patterns made from pieces of tin, a part of a cheese box or round blocks of wood. These two sections can be made as one, if desired, as the two patterns can be combined and by drawing or lifting upon the largest section of pattern it is easily removed from the mold. This mold may be placed either way, in the position shown, or with the bowl of vase uppermost; the only advantage is that by having the bowl downward the concrete is the easier placed. The core to mold the inside of the bowl can be made of any material, sand, plaster, clay, or concrete, as it is a simple form easily modeled with the aid of a wood template. It should be modeled upon a circular board, exactly the size of the core, so that it can be handled and placed without breaking apart; as soon as first section of mold is in position, the core is set within same, using care to have it properly spaced so to be exactly in the center, the other sections of mold are placed around same. When the work is molded in the opposite position to that illustrated, the core must be dispensed with and the space inside bowl modeled with a template or trowel; which is |