Studio: international art (45.1909)

The Making of Plaster Casts

be done in plaster piece-moulds, wax or
gelatine moulds. Plaster piece-moulds
are generally used for casting figures in
the round. The mould is put on in
sections (hence the name), so that every
piece will draw from its own surface.
There may be a considerable number
of pieces, all held together by each part
being locked into the other. For in-
stance, a bust may consist of about
seventy pieces. The casting is done as
in waste moulds, except that in round
figures the mould must be continually
rolled over and over as the plaster is
filled in, so that the finished production
may be hollow with an even thickness
all over. The mould can be removed

FIG. 4.—CHIPPING THE WASTE MOULD

accordingly proceeds all
the more carefully. Thus
the mould can be used
once only — hence the
term waste mould (Fig. 3).

The castings are now
removed to the drying
chamber (Fig. 5), where
the temperature is about
100 degrees. Care must
be exercised at this stage,
and the exposure regu-
lated according to circum-
stances.

Repeat casting can only

FIG. 6.—MAKING CASE FOR GELATINE MOULD

FIG. 5.—DRYING CHAMBER: CLEANING CASTS

in the original sections and used again
as may be desired. Casting from one-
piece plaster moulds can only be done
when there is a plain surface or mould-
ing which will draw all one way. In
this process a “reverse” running mould,
which is practically either a wooden or
iron template, is used. This is run with
plaster on the bench, stopped and
mitred as required, and now forms the
“ reverse.” The mould is then varnished
and oiled, the plates being filled in as
already described. Any number of
casts can be taken from such a mould.

Wax moulding permits of consider-
able ornamentation, but at the same
time there may be no “ undercut.” The

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