RERAMIC STUDIO 
195 
No. 52. Two slate molds, die cut. XIV.-XV. centuries. Cluny Museum, Paris. 
discover any accidents ; such as air bubbles which may have 
formed during the flow of the plaster, or fractures made 
when the plaster was loosened. 
To prepare the plaster, the operator puts into a vessel 
whose inside surface is perfectly smooth, the quantity of 
water which he judges necessary. To whatever the quan- 
tity of water, he adds three-fourths the same amount of 
plaster ; : proceeding slowly until it nearly reaches the level 
of the water. He allows it to stand a few minutes, then he 
stirs it with the spatula (Fig. 3) without beating, until the 
mixture begins to thicken; next, with the spatula or soft 
brush, he spreads the plaster, while still liquid, thoroughly 
over the modeling; finally pouring the remainder over 
the piece. This process should be finished in one casting 
if possible. 
If, accidentally, certain details of the modeling do not 
"draw," an iron tool will remove the plaster which tore 
away the wax, and, by this means, the removal of the cast 
in relief about to be taken from this plaster mould, will be 
made much easier. 
Second Casting. 
The workman now coats his mould regularly and plenti- 
fully with a mixture of common soap melted in water, hav- 
ing the consistency of a thin sauce; after the plaster has 
absorbed the soap, he brushes it lightly with oil, so as to 
form a glaze which will render the plaster to be moulded 
impervious. 
Now again he carefully prepares fresh plaster, neither 
too thick nor too thin, and pours it into the mould, provid- 
ing against air-bubbles and lumps, and covering with ex- 
treme care every detail of the modeling; to this end, remov- 
ing, if necessary, and repacking the plaster. The mould 
being filled, the workman waits until the plaster has thick- 
ened. When it feels hard beneath his finger-nail he care- 
fully loosens it from the mould. 
If the proof be successful, he repairs this cast in relief, 
taking care to weaken the low details, which are very liable 
to be exaggerated when worked out because they differ in 
tone from the plaster background, and, when chased, are 
always accentuated. 
This series of special operations ended, the plaster cast 
in relief must be subject to a new experiment; care being 
taken to preserve intact the margin around the contour, to 
which reference has already been made. 
The workman now places upon this margin an addition 
technically termed neck (Fig. 4, 5, 6, A), in order that he 
may begin to construct the mould which he wishes to per- 
fect. 
Whether this neck be added in plaster, or in wax, it 
is imperative that it be made before a hollow cast is taken 
from the cast in relief above described. 
Third Casting. 
The cast in relief must be rubbed with soap ; care being 
taken not to dull the modeling by the use of a hard brush ; 
next, it should be lightly oiled; then, the margin and the 
neck must be surrounded by a thin and very even band 
of wax, or plastiline, which will serve as a wall for the liquid 
plaster. 
The height of this band, which should not vary a hair's 
breadth, must be from one to two centimeters above the 
margin, according to the thickness to be given to the cop- 
per mould, and the degree of resistance required. 
Care must be taken to make the plaster adhere to the 
margin and the neck, so that the plaster does not injure 
the casting by flooding, and that it remains within the 
limits prepared for it. 
The plaster must again be prepared, stirred very lightly 
with the spatula, and poured on quite gradually, so that it 
enters every small detail of the modeling, and does not 
give rise to air-bubbles. To effect this purpose a brush 
could be used in case of necessity. 
In order to give the cast its proper thickness, when the 
plaster begins to "set", the workman follows the general 
outlines of the piece. With a wide spatula and a light 
touch, he spreads the liquid over the less covered parts, so 
as to obtain a well distributed and even layer. 
When the plaster is set, (this is evident by its tempera- 
