| SULPHO-PLASTICS
This plastic is particularly adaptable for making molds and light castings
requiring tensile strength but very clear outline. It may also be used
for making ornaments and novelties. However, as this is flammable, do
not use for ashtrays.
While the name would convey the thought of plastic sulphur which is
an unstable allotropic form of sulphur, this is not the case, as the sulphur
acts as a bond to hold the filler together and forms a stable material.
Interesting marble effects may be obtained by varying the filler used;
and by substituting a small quantity of chalk to replace some of the graphite,
a very pleasing glazed surface marble is formed.
As long as the graphite is retained as a filler, this plastic may be
electroplated and forms a very economical base for such work.
FORMULA: Mix thoroughly and smoothly together 25 parts of GRAPHITE and
75 parts SULPHUR and place over even heat. (Do not use open flame.) As
soon as the mass has melted and runs like water, remove from the heat.
In any case, a temperature of 235 degrees F. not be exceeded. If heated
about 250 degrees F. the plastic will form a rubbery mass and will have
to be cooled and reheated. In this liquid state the plastic is ready for
casting and may be poured into smooth surfaced molds.
N.B. to heat this mixture properly, a good even heat is necessary. Should
the heating be done by flame, the container should be placed in a sand
bath to insure an even heating surface. The cast-iron top of a heater
or stove is excellent.
EQUIPMENT: The only equipment for the above that is required is space
enough to work in, a stove or heater, a pan to heat the mixture in and
a bench or table.
PROCEDURE: Before making any casting you will need a pattern. After
choosing a design that fits your need, your next step is to make the mold.
Then you may start into production. If your product requires any holes,
threads or machining, this may be done in the same manner as in working
with a metal casting.
Always think of your castings as metal, for they have metallic properties,
i.e., they conduct heat, electricity and can be electroplated. In fact,
the most valuable quality of Sulpho-Plastic is the fact that it can be
used as a metal substitute. This permits you to make products that look
and are as good and even better, in some cases, than a true metal. For
instance, to make a chrome plated metal lamp base or other metal casting
would require foundry equipment and machine shop work and in all, a process
miles out of the reach of the small manufacturer. However, with our plastic,
a lamp base, similar in all respects, may be made for a fraction of the
other cost.
ELECTROPLATING: While this can be done at home with very little equipment,
it is advisable to have it done by a commercial electroplater, who does
it very cheaply and much more efficiently. Electroplating is only used
on expensive replicas and is not advisable for a start.
DESIGN: The number and variety of articles that can be manufactured
from Sulpho-Plastic is practically unlimited and to make a complete list
would be impossible. However, any article of reasonable size and simplicity
of design such as lamps, curios, buddhas, elephants, vases, plaques, brooches,
desk-sets, toys paper weights, etc., may be cast by using an original
or purchased article for a pattern or model - or an original design may
be patterned in clay and used to make a mold. It is advisable for the
beginner to choose a simple article for a start, preferably solid, such
as paper weights or book-ends.
MOLDS: Molds may be made of metal or plaster of paris. Metal molds,
however, require a great deal of skill and equipment to produce. Therefore
for the beginner, it is advisable to use plaster of paris.
To make plaster of paris molds; first obtain a box, wood or cardboard
will do; about an inch longer each way than the article to be cast. Coat
the inside of the box very thoroughly, yet thinly, with stearine or sweet
oil. Use this also on the article to be cast. This acts as a lubricant
and the plaster of paris will not cement itself to either the box or the
article, if the oil is evenly distributed.
Now, next make a thick, creamy mixture of plaster of paris by sifting
the plaster gradually into the water, stirring constantly to prevent lumping.
Let this stand a few minutes to allow the air bubbles to escape. Pour
mixture slowly over pattern in this box to about double the thickness
of the pattern.
Allow several hours to dry, then remove. If the stearine or sweet oil
was applied properly, this will be easy. When the mold is thoroughly dry,
give it a coat (thin) of shellac and repeat in 12 hours. Mold is now ready
for use.
MOLDING: First and foremost always make sure that you have lubricated
your mold with beeswax or stearine. Place molds on a reasonably level
surface and pour the sulpho-plastic into the mold, quickly and smoothly.
Do not pour from a height as this will break the lubricant and leaves
blemishes on the casting. Plastic must be poured quickly to prevent cooling
in folds and thus making a poor casting. One of the big assets of sulpho-plastics
is the fact that it dries and hardens almost immediately. There is no
long wait for casting to dry. |
