The workingman's advocate. [volume] (Chicago [Ill.]) 1864-1877, 1871-04-08
TO BIZ CONTINUED.
Methods of Casting.

Methods Of Casting.
TO CAST IN PLAsrER-Obtain some
fine plaster Of good color, and pass it
through a muslin sleeve, to remove any
coarser PARTICLES which may be present
By mixing gum-arabic with the water in.
tended to be used in the plaster, not only
will the plaster be rendered very hard when
it sets, but beautiful gloss will be given
10 the surface. Care must be taken 10 drop
the plaster powder gradually into the water,
aud to permit the bubbles to rise before the
mixture is stirred otherwise it will become
lumpy. The plaster fhould be Of the con-
slstence Of the yolk Of an egg, and Of
course used Immediately. If the medal in
tended to be copied is a valuable one, with
a smooth surface, it will be advisable not to
oil it, as, in cleaning the oil off, the polish
cav be injured; but if the surface be rough,
th'r will he no re Ledy, and the oil must
ait,I lard be removed by dabbing the sur
face he metal gently with a soft cloth.
A rim 4 thin lead, brass, copper, or even
oiled paper, is then tied around the medal
and some liquid plaster in the first place,
stippled over its surface with soft brush,
to prevent the formation Of air-bubbIes, as
well as tC insure its insertion into TIE most
minute crevlces after which the plaster is
poured upon the surface to the thickness Of
hah an inch, or an inch if large medal.
To cause the separation of the mould from
the metal, all we have to do is to immerse
it in water, when it is readily removed :
otherwise, the mould is sure to be broken.
To obtain a plaster cast from this mould,
we must oil 1t with warm boiled linsed oil,
and allow 1t several days to dry. When
ever the mould is used, it must be well
oiled, otherwise tile surface Of the castings
will be destroyed. The best olive oil must
be used, or the color If the plaster will be
injured.
To CAST IN WAx-The mould is first
made il plaster; but before being used is
placed in warm water, Of hich It Is allow.
ed to absorb as much as it will take-oil
not being used in this process. The surface
must then be allowed to dry, OF the wax
would not adhere closely Pure wax is too
greasy for the purpose, and bladder flake
white is therefore mixed with it. The
quantity can not be stated, but the addition
Of too much gives wax the appearance of
plaster, by taking away its richness. Ii
the wax is often Temelsed, its color is IN
jured. In order to obtain a gray marble
color, marble powder, procurable Of any
I ut raIyaH NTH
only gives beautiful appearance to i, but
renders it more durable The wax is poured
into the mould, and allowed to flow over
its surface, and by mostening the plaster
7 mould in water when the wax has become
hard, the cast is easily removed Wax
models may be fastened by means Of boiled
liuseed-oil and ti3ke-white, and also By a
combination Of beeswax and resin
4 To CAST IN SULPHUR il yery
permanent mode but as a mould it can
only be used for plaster, for hot wax or sui
phur would injure it, surface. When sui
phur is heated 70 the temperature suitable
for forming casts it becomes nearly black
and has, therefore, to DC covered with yer
million in the proportion of one ounce of
vermllllon to three of SUI phur. The sur
face Of the mould, however, need only be
coated with this expensive mixture, and
common sulphur added in any quantity.
4 \ on must Use wood to stir the sulphur, as
iron will take away It's color. The sulphur
will take fire in melting unless it is proper
\ ly stirred, and at first will become thick and
vlscid hut by continuing the application
Of heat it will again assume perfectly iq-
uid form
To CAST IN GLUE-If a medal is SO
much sunk and engraved that you can not
get plaster cast off, mould may be oh
tanned by pouring glue upon it. In this
manner a bunch OF grapes can be taken in
the natural state, and by cutting the glue
down the centre, the grapes can be extricat-
ed, and the moulds used % produce rep
resentation of the origin in plaster. Isln-
glass may be similarly used, but it is first
mixed with tlake-whte in the state Of pow
! der.
To CAST IN BREAD PAsrE-Take the
inside of penny roll and work it we'll up
with vermilon, the longer the better, until
it becomes viscid and tough it is then to
be worked well into tile mould After
having obtained the mould, it must be fast
ened down upon piece Of wood BY victim
it, 50 as to prevent it from warplng as (
dries. After it has been thoroughly dried,
YOU may oil it, and then obtain as many
casts as you please from it in plaster, wax,
or sulphur BY means Of bread paste, a
traveller may always take a mould Of any
small object Of interest be meets WITH on
his journey, and thus proper knowledge Of
its mode Of use becomes invaluable Cab
met Maker.