SCIENCE 
IS 
KNOWLEDGE. 
KNOWLEDGE 
IS 
POWER. 
A PRACTICAL JOURNAL OF 
HOME ARTS 
Vol. VI. 
NEW YORK, JUNE, 1883. 
No. 6. 
Casting in Plaster of Paris.— IV. 
BY MARK MALLETT. 
lECE-MOULDS 
are made of plas- 
ler, but in sec- 
tions so arranged 
that each piece 
can be pulled, 
without obstruc- 
tion, from the 
cast. That they 
may thus ' leave ' 
freely often ne- 
cessitates that 
these sections should be very small and 
numerous. In making a piece-mould for 
a face, for instance, a dozen pieces or 
more will often have to be made. 
A piece-mould cannot be taken direct 
from the clay model. A cast must first 
be made by means of a waste mould. 
This cast must, as a first step, be rubbed 
over with a little lard, which, on account 
of its whiteness, is better than oil or any 
other kind of grease, as it will not dis^ 
color the work. This is to keep cast and 
mould from sticking together. A little 
plaster must then be mixed, and the first 
section of the mould built up with the 
spatula on the cast. It will have to be 
made some three-quarters of an inch or 
more, according to circumstances. 
When this piece has set, it can be 
pulled from the cast, its sides trimmed 
round with a knife, and lard must be 
rubbed over them. It must then be re- 
placed, and two more pieces can be cast 
on two of its opposite sides, the outer 
edges of which will, in their turn, require 
paring and greasing, and the work can 
thus be carried on until Ihe whole cast 
has been mapped out and covered with 
pieces larger or smaller, as the necessity 
for making them "leave" the surface 
freely may demand. 
Lastly, an outer mould or shell, in two 
or more large pieces, to envelop and ])ind 
all the small pieces together, has to be 
made. Before the mould is filled these 
have, in their turn, to be bound and tied 
together with string. When this has 
been done— so closely will all the differ- 
ent pieces which have been cast one upon 
another, necessarily fit together— the 
