Made of such materials as gelatin, vinyl, and rubber, flexible molds are used for producing more than one cast they offer a much simpler alternative to piece molding when the original model is a rigid one with complex forms and undercuts. Piece molding is a highly skilled and laborious process. When the mold has been filled, it can be removed section by section from the cast and used again. The mold sections are carefully keyed together and supported by a plaster case. The number of sections depends on the complexity of the form and on the amount of undercutting tens, or even hundreds, of pieces may be required for really large, complex works. A piece mold is built up in sections that can be withdrawn from the original model without damaging it. Before the invention of flexible molds (see below), piece molds were used for producing wax casts for metal casting by the lost-wax process. Plaster piece molds are used for producing more than one cast from a soft or rigid original and are especially good for reproducing existing sculpture and for slip casting (see below). The order of reassembling and filling the mold may be reversed fibreglass and resin, for example, are “laid up” in the mold pieces before they are reassembled. ![]() This involves the destruction of the mold-hence the term “ waste” mold. Fourth, the mold is carefully chipped away from the cast. Third, the mold is cleaned, reassembled, and filled with a self-setting material such as plaster, concrete, or fibreglass-reinforced resin. ![]() Second, when the plaster is set, the mold is divided and removed from the clay model. First, the mold is built up in liquid plaster over the original clay model for casting reliefs, a one-piece mold may be sufficient, but for sculpture in the round a mold in at least two sections is required. They are especially useful for producing master casts for subsequent reproduction in metal. These are used for producing a single cast from a soft, plastic original, usually clay. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning. ![]()
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