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Question: WHY HAS YOUR #80 FORMULA REMAINED
THE SAME FOR SO MANY YEARS?
“If it ain’t broke, don’t fix it”. This
adage is true for the #80 formula. Unlike Silicones and Urethanes,
where the shore hardness must be variable, Natural Latex molding
compound #80 dries to a very flexible rubber with a shore hardness
that is superb for concrete and plaster. If the #80 is vulcanized
properly, several castings with polyester resin can be made. The
problem with formulating natural latex molding compounds is that
variations complicate the
mold making process. Natural Latex is also a difficult product to
control in compounding. If #80 is not compounded according to its
time-tested formula, it will veer out of control. Exacting quality
control has made our Natural Latex Molding Compound #80 the standard
of the industry. |
Question: IF MY LATEX IS TOO THICK,
MAY I USE TAP WATER TO DILUTE THE LATEX?
Tap water is not a very good thinner for latex since it may contain
Calcium and Magnesium salts. Even small amounts of the salts of
Calcium and Magnesium have a tendency to coagulate the latex. Hard
water must never be used. |
Question: WHAT IS BEST TO USE TO THIN
LATEX?
If you wish to thin out the latex, simply use distilled water or
bottled water. Read the label carefully, several bottled waters
contain calcium. |
Question: HOW CAN I THICKEN THE LATEX
TO FILL IN DEEP UNDERCUTS?
Use CECO Powder. It will thicken the latex to a point where it can
be applied with a trowel. It will also strengthen the latex. Only
mix CECO Powder in backup coats after the first few coats have been
applied. |
Question: HOW LONG SHOULD I HEAT THE
RUBBER TO COMPLETE
THE PROCESS OF VULCANIZATION?
Vulcanization is the combination of Latex with Sulfur in the presence
of heat. (Remember Goodyear?) If a rubber is not vulcanized, it
has poor keeping qualities and usually does not keep its original
form, especially upon stretching. I would recommend 24 hours at
100- 120 degrees farenheit Let it stay at room temperature for about
3 days before starting your fiberglass back up. |
Question: WHAT EXACTLY IS VULCANIZATION?
If we avoid all academic discussions about Vulcanization, we can
say that Vulcanization is named after Vulcan, the ancient Roman
host of fire, and it is the combination of various ingredients with
the rubber under controlled heat to create a flexible elastomer.
Rubber that is not vulcanized is usually hard under low temperature
and very soft at high temperature. Un-vulcanized rubber is also
"e;tacky"e;, and when
stretched, deforms very easily. Un-vulcanized rubber shows "e;plasticity"e;
as opposed to "e;elasticity"e;. Vulcanization corrects these
defects while greatly
increasing the tensile strength of the rubber. |
Question: WHY DOES LATEX HAVE AN AMMONIA
SMELL?
Latex comes to us from the plantation before we begin compounding
it. Its compounded here. Ammonia preserves latex and is also anti-microbial.
Its a long way from the Far East. |
Question: LATEX SOMETIMES HAS A HEAVIER
AMMONIA SMELL WHILE AT OTHER TIMES IT IS A LITTLE MILDER.WHY?
Cementex imports latex directly from several sources in the Far
East. Sometimes the latex gets contaminated by bacteria. Since ammonia
is used not only as a preservative, but also as a fungicide, the
stronger smell indicates that more was needed to combat bacterial
action. You may also notice a reduction in viscosity associated
with the additional ammonia. |
Question: DO YOU PREFER AMMONIATED LATEX
OR "e;NO"e; AMMONIA LATEXES FOR MAKING MOLDS?
We prefer higher ammonia concentrated latex. One of the basic reasons
is that latex preserved with alkali has a marked tendency to be
"e;sticky"e; and "e;tacky"e;. Another reason is that
non-ammoniated latex has a tendency to absorb water so that evaporation
is very slow. This means long waits between coats. Our #80 ammoniated
latex is designed to coat about every hour as opposed to the de-ammoniated
latexes. |
Question: HOW LONG DOES YOUR #80, #660,
AND SIMILAR BRUSH-ON MOLDING COMPOUNDS LAST?
The shelf life of Natural Latex is anywhere from 6 months to a year.
It has optimum qualities till about 6 months and then slowly loses
some of its mold making characteristics. It takes about a year for
it to lose almost all of its properties. If it separates into 2
layers, gentle stirring with a stick will bring it back. If it looks
like cottage cheese, it should not be used. |
Question: IF LATEX "e;SEEMS"e;
OK AFTER 6 MONTHS, WHAT SHOULD I USE IT FOR?
Use it for back-up coats. If it is still brushable, you may use
it, but for back-up coats only. |
Question: HOW LONG SHOULD I WAIT BETWEEN
COATS OF LATEX?
Our products, #80, #660, etc., are designed to be coated about every
hour. This is not a hard and fast rule and judgement is required.
You do not have to wait a few hours between coats. However, avoid
waiting more than 25 or 30 hours between coats. |
Question: MY BRUSHES DRY WHEN I COAT
LATEX ON MY MOLD.WHAT SHOULD I DO?
Keep several inexpensive brushes in thick,soapy water. Use Ivory
liquid soap or Murphy's oil soap, or something similar. Remember
that latex dries by the evaporation of water, so, naturally, your
brushes would get all "e;gummed"e; up. Remember to shake your
brushes out well before you begin coating.
After your brush gets stuck, place it back in the soapy water and
switch to another brush. Comb your previous brush out with a fork
or dog comb. If you still have dried rubber in your brush, soaking
the brush in lacquer thinner will help a lot. |
Question: WHAT DO I DO IF I GET A BUBBLE
OR A BLISTER WHEN
I AM BRUSHING ON THE #80 LATEX COMPOUND?
Burst the bubble with a pin or use a syringe to withdraw the air.
When burshing, brush up and down and left to right. This helps burst
the bubbles. Then simple continue brushing. |
Question: WHAT IS THE “ BRUSH
ON METHOD” FOR MAKING MOLDS?
The “Brush on Method” for making molds has always been
associated with natural latex. It is the process of applying the
rubber, like pthick paint, with a brush. The mold is built up through
multiple layers applied with a brush on top of each other. Urethanes
and Silicones are also referred to as “Rubber”. Remember,
though, only natural latex, when brushed layer upon layer, has the
superior flexibility needed for making concrete and plaster reproductions. |
Question:WHO DISCOVERED THAT NATURAL
LATEX ADHERES TO ITSELF?
For that again return to the practices of ancient civilization.
The natives of Central America noticed that when they cut fresh
natural rubber ( milk of weeping trees), the cut ends adhered to
themselves. The same principle is applied to mold-making. Freshly
coated latex accepts another coat of latex so it is possible to
build up your layers. Don’t forget, though, about 48
hours is the limit before adhesion problems begin. |
Question:WHEN DID THE PRODUCTION OF
HOLLOW OBJECTS ACTUALLY BEGIN?
Since we are speaking about products to produce hollow objects,
the answer to you question can be found in ancient civilization.
When early explorers landed in the “New World”, they
noticed that the natives poured the milk of “weeping trees”
into clay formers to build up layers of this milk of the weeping
tree. The natives then broke the formers and retained the “rulling”
material that was formed. These formers were actually used to produce
water bottles or to waterproof cloth. In the 1800’s, the industry
turned to Peaster of Paris to make hollow objects out of rubber.
The 1880’s added another dimension to the production of hollow
objects by using fillers to harden the latex. In addition to SP-100,
Cementex compounds L-200 casting compound and #64 filler so that
you may vary the degree of hardness. |
Question: WHAT CAN I DO TO PRODUCE HARD
HOLLOW OBJECTS?
Hard, hollow objects can be produced by using SP-100, our new casting
compound. SP-100 is a one-partlatex that produces hard hollow objects
through a process of casting into a plaster of paris mold, using
the slush casting method. |
Question: HOW DO YOU REPAIR A NATURAL
LATEX MOLD WHEN IT TEARS?
When a tear develops in a natural latex mold, it is very difficult
to repair it completely for long runs. It may only be repaired temporarily.
The best method we foulnd is to clean the area around the tear with
acetone. Then soak some gauze in natural latex, squeeze out the
gauze and place it in the tear. Hold it together until it sets a
little and then trim the gauze. Then put a number of coats of latex
over the gauze. Let it vulcanize. The repair should hold for another
ten castings, or so. |
Question: WHAT IS NEOFLEX?
Neoflex is a new blend of rubber produced by Cementex. It is low
in ammonia, durable, and easy to use. It’s flexibility is
matched only by it’s durability. |
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