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| Sprayable
Polyurethane Mold Rubber |
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Gel
- Self Thickening RTV Liquid Rubber
Features
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- Tough,
with high tear strength
- Easy
1:1 mix, by weight or volume
- Good
grease and oil resistance
- Good
adhesion between coats
- Fast
- one day molds
- Good
flow into fine detail
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Description
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Gel
mold rubbers consist of two liquids, Part A and Part B. They
immediately gel to a brushable or trowellable texture and
cure overnight at room temperature to a flexible, tough RTV(room
temperature vulcanizing) rubber after mixing one to one by
weight or volume. Gel mold rubbers are perfect for molds built
up with a brush, spatula or spray.
Gel 40 yields the
most liquid mix for optimum air bubble release, easiest brushing
and cures to a Shore A hardness of 40. Gel 50 is an excellent
adhesive for bonding polyurethane rubbers to many materials
and yields a thicker mix and cures to a tougher 50 Shore A
hardness. New, Gel Spray 50 consists of a blue Part A and
a yellow Part B that yield a green mixture.
The mix changes
color and thickens to a buttery non-sag paste with a working
time of about twenty minutes as the liquid components of Gel
are stirred together. A mold can be built up in two or three
coats, with each coat applied about one hour apart. The mold
can be completed in several hours. Sprayed molds can be finished
in a single application. The rubber will cure overnight at
room temperature to a tough skin mold that can be reinforced
with fabric if desired. |
Using
the Mold
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When
Gel mold is turned inside out like a sock, the outside surface
must be lubricated with soapy water or petroleum jelly so it
slides over itself effortlessly. The shell or mother mold may
be made of plaster, polyester resin and fiberglass, 15-6, 1512X
resin or Poxy using Fiber and fiberglass or with Gel Plastic-75.
Mold shells can also be formed by spraying Gel Shell. |
Low
Viscosity for First Coats
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For
a bubble-free primary coat, Gel 40 should be used because Gel
50 may be thinned by combining identical components of 74-30.
This will result in a semi-liquid, easily brushable, mayonnaise
texture that allows bubbles to rise. Equal parts of Gel Part
A and 74-30 Part A must be combined and stirred together before
74-30 is used to thin Gel rubbers. Then, mix in equal parts
of Gel Part B and 74-30 Part B. Distortion will occur if Gel
40 or 50 is brushed over 74-30. If only 74-30 is used, the mold
should be finished with 74-30 thickened with Cab-O-Sil. |
Thicker
Mixes for Filling Undercuts
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Gel
rubbers can be made even thicker by stirring Cab-O-Sil into
the mixed rubber. |
Faster
Cures
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Gel
Part X can be added to increase the rate of the cure of Gel
Spray 50. Thoroughly mix approximately 0.25% into Part B before
mixing with Part A to demold in several hours depending on temperature.
For a slightly harder rubber, use Part X. |
Uses
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Gel
mold rubbers are suggested for evaluation as a mold material
for plaster, cement and waxes, and limited casting with polyester,
epoxy and polyurethane resins. They exhibit adhesion to many
polyurethane rubbers and may be used for restoring torn molds
with fabric reinforcement. |
Packaging: |
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Containers |
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Size |
Net lbs. |
Product |
Weight/lbs. |
A |
B |
A |
B |
Gel 40 &
Gel 50 &
Gel Spray 50 |
4.0 |
1 qt. |
1 qt. |
2.0 |
2.0 |
16.0 |
1 gal. |
1 gal. |
8.0 |
8.0 |
80.0 |
5 gal. |
5 gal. |
40.0 |
40.0 |
Gel Plastic-75
Mix Ratio
1A to 10B |
900.0 |
55 gal. |
55 gal. |
450.0 |
450.0 |
Gel 50 Part X: 1 pint (1.0 lb.), 1 gal. (8.0 lbs.) |
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