Moulding and Casting

SILILCONE RUBBER - Platinum / Addition Cure Silicones

Addition-cure silicone rubber may be inhibited by certain contaminants in or on the pattern to be moulded resulting in tackiness at the pattern interface or a total lack of cure throughout the mould. Latex, sulfur clays, certain wood surfaces, newly cast polyester, epoxy or urethane rubber my cause inhibition. If compatibility between the rubber and the surface is a concern, a small-scale test is recommended. Apply a small amount of rubber onto a non-critical area of the pattern. Inhibition has occurred if the rubber is gummy or uncured after the recommended cure time has passed. To prevent inhibition, one or more coatings of a clear acrylic lacquer applied to the model surface is usually effective. Allow any sealer to thoroughly dry before applying rubber. Note that even with a sealer, platinum silicones will not work with modeling clays containing heavy amounts of sulfur.

Dragon Skin / Sorta-Clear 40 / Smooth-Sil

• Dragon Skin - Dragon Skin and Dragon Skin Q are high performance platinum cure silicone rubbers that can be mixed 1A:1B by weight or volume and cure at room temperature with no shrinkage. Cured Dragon Skin has a shore hardness of 10A (very soft), and it is very strong. It will stretch many times its original size without tearing and will rebound to its original form without distortion. Dragon Skin is water white translucent and Silc-pig pigments can be used for creating color effects. It is perfect for masks, prosthetic appliances, and intricate moulds. To increase the viscosity use Thi-Vex, and thin with Silicone Thinner.
  
  - Making a brush on mould using Dragon Skin

• Sorta-Clear 30 - Sorta-Clear 40 is a water white translucent silicone rubber that is designed for extracting models via cutting. This platinum cure silicone cures at room temperature with no shrinkage. These silicones exhibit good chemical, abrasion and heat resistance. Sorta-Clear rubber is ideal for making prototype, jewelry or other moulds of any configuration where model visibility is important. Materials such as plasters, concrete, wax, low-melt metal alloys or resins (urethane, epoxy or polyester) can then be cast into these silicone rubbers without a release agent. SORTA-Clear can be pigmented with SILC Pig silicone pigments.
  
  

  - Using Sorta-Clear to cast wax jewelry masters

• Smooth-Sil 950 - Smooth-Sil 950 is Shore A 50 hardness, and is ideal for things like moulds to make simple urethane foam columns, pressure-intensifiers for composites, and for any application where the object is not a complicated shape. The silicone is mixed 100A:10B by weight, which requires an accurate gram scale. No post curing is required and the material cures with virtually no shrinkage. This is ideal for reproducing the finer details of a model. Materials such as urethane, urethane foams, epoxies, polyester resins, wax and low-melt metal alloys (tin, pewter) can be cast into Smooth-Sil Silicones without application of release agent.

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