Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

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Forms for Architectural Concrete 407
A full-size model of the ornament is made of wood, plaster, or some
other suitable material. Then, using this model as a pattern, the waste
mold is cut, either as a single unit or in parts to be assembled later. If
a single-piece mold will be too heavy for easy erection, the mold
should be cast in two or more parts. The back of a mold should be
shaped to permit it to fit accurately against the backing forms, sheathing,
studs, wales, or blocks. Figure 14-7 illustrates form assemblies
using waste molds and backup lumber.
Some molds are attached to the structural members of forms with
nails that are driven through the plaster into the lumber. The nail
heads are countersunk, and the holes are pointed with patching plaster.
If the plaster is too thick to permit the use of nails to fasten the
molds to the form members, holes may be drilled through the plaster
to permit the use of wires for fastening purposes. The wires can be
embedded in the plaster and covered with patching plaster to restore
the original surface condition to the mold.
It is usually necessary to destroy a waste mold when it is stripped
from the concrete, which may require some chipping with a cold
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FIGURE 14-7 Plaster waste molds. (Source: Portland Cement Association)
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