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Making Molds with Natural Latex
Number 80 (Natural Latex)
#80
has been manufactured by Cementex since 1946. It is a "e;timetested"e;
formula which has been used by mold makers the world over.
Number
80 is a vulcanizeable Natural Latex compounded from specially processed
Latex with a solid content of between 68 and 70 percent, which minimizes
shrinkage. Number 80 is therefore suitable for making rubber molds
by painting, brushing or spraying. The special method of compounding,
and its high solid content, permit reproduction of the finest detail.
Its major uses have been in the manufacture resin figures, ornamental
wax candles, and isostatic molding bags.
Number
80 also has the following additional characteristics:
- High Latex stability and long storage life
- Films that are very tear-resistant
- Excellent
resistance to aging & sunlight
- Exceptionally
long runs while casting concrete, plaster, waxes and certain metals
- Continuous
uniform batches made under strict quality control
- Shrinkage
is minimal
Number
80 is preserved with ammonia, and has a distinct ammonia odor to
it.
Number
80 also has a distinct thickening agent called CECO Powder. This
powder has been developed after many years of research. In addition
to thickening the Latex without "e;clumping,"e; CECO Powder
helps improve the strength of the rubber as well as its resistance
to degradation by the casting materials.
TECHNICAL
DATA ON NUMBER 80
CATEGORY
Latex
# 80 is a formulation compounded from a specially prepared high
solids content natural latex. It is of the vulcaniseable type. This
means that after you have completed the buildup of coats on your
model, heat or time must be used to bring about the final cure.
VULCANISATION
Vulcanisation
is the process of causing the Latex to complete its final process
of cross-linking. This can be accomplished by either time or heat.
The time recommended is approximately 3 days at room temperature.
If heating is chosen, it is recommended that you heat the completed
rubber mold on the model for approximately four hours at 120 degrees
Fahrenheit.
TESTING
FOR VULCANISATION
In testing
for Vulcanisation, the following procedure is usually advisable:
After being certain that the Latex is not tacky, take a sharp object
and make a small indentation in the Latex. It should spring back
within an hour. Only a small fraction of the indentation should
remain. If more than a small fraction remains, then heat the Latex
for about another hour. This should be sufficient to bring about
the total cure.
SOLIDS
CONTENT
Latex
#80 is approximately 66-68 percent solids.
ODOR
Latex
#80 is compounded with ammonia. It has a distinct ammonia odor.
Ammonia is one of the most common preservatives used in Latex when
it is shipped from the plantation.
CHARACTERISTICS
- High
latex stability.
- Long
storage life.
- Vulcanized
molds have excellent resistance to tearing.
- Excellent
resistance to sunlight and aging.
- Uniform
batches made under strict quality control.
SHRINKAGE
All
latex has a tendency to shrink. Latex #80, however, because of its
high solids content, shrinks very little. When making your model,
an allowance for shrinkage should be made.
STORAGE
Latex
#80 has
a shelf life of approximately one year if kept in a cool place.
The Latex will turn into a cottage cheese consistency when it
is spoiled or will develop a putrid odor.
USE
Latex #80 is the old standby of the following industries:
Plaster
Our #80 Latex has been used by those who pour plaster since
the end of World War II. It has great resistance to the heat that
is generated by the Plaster and maintains excellent detail. The
ingredient characteristics of this Latex are such that no release
agent is needed when casting plaster.
Concrete
Latex
#80 has also been used by those who pour concrete since the end
of World War II. Very long runs have been obtained by producers
of Lawn and Garden Ornaments and similar items made from concrete.
Wax
Latex #80 has good resistance to the heat generated by wax.
Although it cannot be used for exceptionally long runs, short and
medium size runs work out very well.
Polyester Resins
Latex #80 can be used when pouring polyester Resins, but only
with limited success. If the Latex is properly vulcanized, runs
of between twenty and fifty pieces with polyester resins can be
obtained. It is important to vulcanize the Latex properly when working
with polyester resins. If this is not done, the heat generated by
these resins, as well as several side chemical reactions, will cause
a rapid degradation of the Latex.
APPEARANCE
Latex #80 is a milky white, or sometimes slightly grey, compound
of medium viscosity.
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