MouldMaking and Casting
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Mouldmaking and Casting is a technical manual of the many techniques of this ancient craft and art form. With step-by-step illustrations, it explains the materials required and the processes involved to create reproductions of a range of pieces. The book covers traditional techniques as well as today's more advanced technical methods.
If the original pattern was not too detailed or undercut it may be possible simply to lift the cast out of the mould, a little suction being the only hindrance. 2. If there is a lot of suction or detail and undercutting preventing the cast coming out cleanly without damage, it may be necessary to remove the mould from the cast. To do this, invert the clay mould and cast, and, holding them together, gently pick away the clay mould from the cast. 3. Once free from the mould, trim and clean the
flexibility. Moulds can be made in one piece if the foot of the mould is large enough to provide access into the mould; otherwise a multi-piece mould will need to be made (see Chapter 2). One-Piece Moulds Making the case is the first stage of the process. It needs to be created around the pattern, and is then filled with liquid Gelflex, which sets to form the mould. Patterns should be prepared as for other Gelflex moulds, depending on the material to be moulded, and secured if necessary to the
the case pieces. Initially, this is just to part the adjoining flange seams of each piece, not to remove the pieces from the Gelflex. 3. Once the flanges have been parted, open up the seams some more by methodically working equally and gradually all the way along them. As the seams start to open it may be necessary to use a chisel, particularly on larger moulds. Larger moulds may also benefit from a series of wooden or plastic wedges being gradually driven into the seam in sequence until the
During the manufacturing process of plaster, the mineral gypsum (CaS042H20) is heated until the water part of it (H20) is driven off, leaving a dry powder (a process known as calcification). When the plaster is mixed with water a chemical reaction takes place in which the plaster takes back the water and sets to a solid again of similar properties as the original mineral. There are some very precise methods of mixing plaster using weights and measures of plaster to water, but in practice most
available electric frying pans with a controllable thermostat built in are very good either to melt directly in, or to heat a separate pan. If the pan does not have a lip, it is a fairly straightforward job to knock one out with a small hammer, and is essential if pouring directly from the pan. ■ Brushes (decorating quality) are needed for the application of wax to the mould surface when hollow casting. ■ Wax modelling tools are required for remodelling and trimming casts. ■ Craft knifes are