 Applications
 There is a full-range of urethane and silicone elastomers specifically formulated for high performance mold-making materials. The urethane and silicone products also have a wide-range of durometers (hardness/flexibility), which provides strength and long mold-life. Both products are two-part; room temperature curing materials that are available for use within 24 hours or less.
Types of Molds and Usage
Polytek urethanes and silicones can be used to produce high quality block molds, poured blanket molds, brushed-on or sprayed molds. For the GRG, FMG and GFRC markets the majority of the molds are, depending on the detail of the master, made from the 74, 75 or 77 Series urethanes. For resin casting or situations where post-finishing requirements prohibit the use of a release agent, silicone molds are used. A general rule of thumb is "the more detail and undercut on the master, the softer the rubber. The less detail, the harder the rubber". Both the urethane and the silicone material can be vacuum or pressure cast for more perfect molds.
Products
74, 75 & 77 Series
The 74, 75 & 77 Series are two-part urethanes for plaster, concrete, GRG, GFRC and Forton® MG castings. They are easy to use and provide long-lasting flexible mold materials. This Series offers a wide-range of durometers.
Polygel® Series
Polygel is a tough, self-thickening urethane product formulated for brush-on molds. Polygel Spray 35 and Spray 50 are available to spray through the VS-3000. Also available is Polygel Shell, which is a sprayable mother mold material. Polygel 75 is a lightweight, but very tough, self thickening urethane for mother molds.
TinSil® & PlatSil® Series
These silicone products can be poured, brushed-on or put in meter mix machines. Certain PlatSil products are available in 1:1 formulations and ready for use in four (4) hours.
15 Series Casting Resins
This series provides a wide-range of two-part urethane casting resins and setting times. These resins will provide excellent detail in tough casting situations. They can also be used as a light weight, yet strong mother mold.
PolyOptic® Resins
This is a clear casting resin used specifically for special effects.
Releases
There is a wide-range of release agents available for all types of moldmaking
and casting. Good releases for concrete, GRG, GFRC & FMG applications include:
- 2300 a silicone spray release, very functional, good to use on the master when making urethane molds. Do not use with silicone rubber.
- 2601 a water based silicone release, good when casting GFRC, pre-cast concrete, GRG, Forton® MG or plaster in urethane molds.
- 2650 a vegetable-based release, to prolong the life of urethane molds when casting concrete or GFRC.
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