The Penn's Grove record., 1884-08-23
MAKING Casts in Plaster,

Europe IL IL T6dll q p"IoloSSlou,duu OHt
in which years of practice are required
in order to obtain proficiency" So
said Mr.. Kretchmer, the sculptor, in
answer to innumerable questions.
1.-THE specimens of celebrated works of
sculpture in America are good, bad,
and Indifferent. Too often they are
the copies Of copies-that is to say.
they are not made in the molds taken
directly from the original, The indni-
tesimal variations in the first copies
differences so slight as not to be detect
ed by eye or measurement-are serious
If continued.
did you ever notice that when a
carpenter is saving several lengths Of
board he always uses the same piece
for a measure ? The reason is, that,
whatever difference or error may occur
in any single measurement cannot be
continued or increased if the original
measured is adhered to.
"But you wish to know how plaster
casts are made ; well, then l must first
impress you with the fact that sculpt-
ure consists of three distinct processes.
First the clay or wax model second,
the plaster copy and, third, the finish
ed work in marble, bronze, or whatever
material is desired. Now, a tinted
preparation of plaster of Paris mixed
with water, of the consistency of rich
cream, is thrown in a thin layer upon
the soft, moist clay model. This is
called the danger coat, and is followed
by a thicker coating of coarse plaster.
sometimes supplemented by iron rods
or sticks imbedded in It to give proper
strength to the mold. In a few mo-
ments the plaster by a chemical ar
rangement sets and becomes a hard,
rigid covering, the inner surface Of
which is close, perfect contact with the
surface of the model, following the very
minutest detail of form and texture.
This covering or mold is divided or
separated into such portions as the
character of the form may render nee
essary by pieces of tin or brass set edge
wise, like a division wall in the clay,
before the plas ter is applied.
when the plaster is hardened Sufi-
GENTLY the several pieces are separated
from each other and from the clay with
but little difficulty. OF course the
clay model is partially and sometimes
wholly destroyed in the process Of re-
moval. Any adhering clay is removed
the surface is carefully washed, and
after the application of oil, soap-suds,
or a solution of soda-to prevent adhe-
sion of the plaster with which the
inner surface of the mold is afterwards
covered-the pieces are adjusted and
firmly bound together.
"We have now a plaster form akin
to a jelly or ice cream mold into which
a preparation of plaster is thrown and
worked, covering the inner surface to
the necessary thickness, and allowed to
harden. The oars plaster and bind.
ing irons of the mold are now broken
off by means of a dull, blunt chisel and
mallet, leaving the plaster cast covered
by a thin coat of tinted plaster. This
danger coat is then carefully removed
by the same means, the previous appli-
cation of oil and soda admitting of easy
separation, while the difference of tint
between the cast and the danger-coat
serves as a valuable guide in the deli
cate operation.
II have already explained to you the
way IN which a copy of a clay model j,
made by means of what is called IA waste
mold. Both model and mold are de-
stroyed or wasted in the operation,
The method employed to reproduce
the cast, or a marble, bronze, or any
other rigid form, without injury to the
original is different and requires great
skill. Indeed, very few of the forma
tones-as men who follow this industry
are called in Italy-and only those Of
exceptional ability, are permitted Il
make copies Of the valuable works con,
tanned in the public and private galler.
les of Europe. The reason for this
the danger attendant on the work.
will explain to you presently.
Reproductions are made by what j
called a piece mold, which is SO arrang
ed that the various pieces can be 1eadil,
removed and readjusted.
THUS, in holding a sphere, or say
an egg, by precision in the dividing line
the mold might be made of only tw,
pieces, as both would draw from thu
object without difficulty. A pear o
irregular shape might require three O
four pieces. And when you eonside,
the ~intricacies of forms in a figure o
group you will not be surprised when
tell you that several hundred or even
thousand pieces are sometimes necessa
ry. These pieces are held together o
keyed by a plaster cover of two or mort
parts called a cask, which serves the
same purpose as the hoops around tn,
slaves of a tub OIL barrel, or a print