Dow Silastic M RTV Silicone Rubber

Dow Silastic M RTV Silicone Rubber Datasheet
  • Description for Dow Silastic M RTV Silicone Rubber

    Good tear resistance, highest durometer, good inhibition resistance.

    *See Terms of Use Below

    Brand Silastic
    Application Type Mold-Making
    1 Part or 2 Part 2 Part
    Material Form Fluid
    Substrate Casting plastics
    Industry Architectural, Architectural components
    Manufacturer Dow
    Chemistry Silicone rubber
    Cure Method Heat, Base/Curing Agent
    Cure Temperature (°C) 25, 25, 52, 65, 93, 121, 149
    Cure Time (min) 960, 960, 60, 30, 15, 7, 5.00
    Viscosity (cPs) 90,000, Pourable
    Color Regal Blue
    Other Resistance Inhibition
    Cut Resistance Cut-growth
  • Technical Data for Dow Silastic M RTV Silicone Rubber

    • Application Type
    • 1 Part or 2 Part
      • 1 Part or 2 Part - 2 Part
      • Part A Name - Base
      • Part B Name - Curing Agent
    • Material Form
      • Liquid - Fluid
    • Substrate
    • Industry
    • Chemistry
    • Application Method
      • Dispenser - Automatic mixing equipment
    • Cure Method
      • Heat
      • 2-Part Cure - Base/Curing Agent
    • Color
      • Blue - Regal Blue
    • Brand
      • Silastic
    Cure Specs
    Cure Temperature (°C) 25, 25, 52, 65, 93, 121, 149 Test Method
    Cure Time (min) 960, 960, 60, 30, 15, 7, 5.00 Test Method
    Viscosity (cPs) 90,000, Pourable Test Method
    Set Time (min) 30 Test Method
    Linear Shrinkage (%) 0.10 Test Method
    Work / Pot Time (min) 90
    Mix Ratio 10:1 (by volume), 10:1 (by weight)
    Bond Strength
    General Bond Strength (psi) High
    Tear Strength (piw) 90 (ppi), Tear Resistance Test Method
    Tensile Strength (psi) 650 Test Method
    Material Resistance
    Other Resistance Inhibition
    Cut Resistance Cut-growth
    Shore A Hardness 59 Test Method
    Elongation (%) 3 Test Method
    Flexibility Firm,Flexible
    Other Properties
    Specific Gravity 1.290 Test Method
    Flash Point (°F) 212.0
    Business Information
    Shelf Life Details Silastic M RTV Silicone Rubber base and curing agent should be stored in closed containers at or below room temperature. The materials have a shelf life of 12 months from date of manufacture. Refer to product packaging for “Use By” date.
    Shelf Life Type from date of manufacture
    Shelf Life (mon) 12
  • Best Practices for Dow Silastic M RTV Silicone Rubber

    *See Terms of Use Below

    1. Surface Preparation

      Certain contaminants used in moldmaking operations can prevent Silastic M RTV Silicone Rubber from curing. Patterns to be molded should be thoroughly cleaned to remove grease, oil and other surface contaminants. Care should also be taken to ensure that corners, crevices and draws are free of dirt or particles of foreign matter. A light “blow over” with compressed air is advised when the pattern has convoluted draws or undercuts. Then, the original model or pattern should be placed in a light frame of cardboard, foil, wood or other material. There should be approximately 3/8-inch clearance on all sides and over the top of the pattern. The patterns should be attached securely to the bottom of the frame so it does not float. A pattern release agent should then be wiped or sprayed on the pattern. Spreading a light coat of release agent on the sides and underside of the top of the frame will facilitate release. A good pattern release agent can be made by combining 5 percent petroleum jelly and 95 percent solvent. Combine the materials and let stand overnight – then shake by hand to provide a good mix.

    2. Mixing

      Automatic mixing equipment handles Silastic M RTV Silicone Rubber efficiently.

      Silastic M RTV Silicone Rubber curing agent should be mixed into the base material just before use (with either manual or mechanical stirring) in the amounts of 10 parts base to one part curing agent by weight. For the best curing results, use metal cans, clean glassware or unwaxed paper containers for mixing the base and curing agent.

    3. Deairing/Degassing

      The product is deaired before shipment when packaged in drums.

      Inclusion of air during mixing may cause avoids in the finished mold. Entrapped air may be removed by applying a vacuum of 28 to 29 inches of mercury. Under such a vacuum, the material will expand to three to four times its original volume. As the froth collapses, the mixture will recede to its original volume. The vacuum should be held one or two minutes longer before releasing. Pressure casting may be substituted with equal success.

    4. Curing

      The cure of Silastic M RTV Silicone Rubber occurs by a reaction between the base polymer and the curing agent. Polymerization requires 24 hours after the addition of the curing agent at room temperature. This material will not revert or depolymerize, even under conditions of elevated temperature and confinement. Vulcanization can be accelerated by heating the catalyzed material. However, this will increase the shrinkage from nil to 0.3 percent. A part 1/4-inch thick will set up within 30 minutes if the temperature is maintained at 150°F (65°C). The rate at which thicker sections will set up depends on the size and shape of the piece.

      See Vendor Technical Data Sheet for more info.

  • Comparable Materials for Dow Silastic M RTV Silicone Rubber

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
25°C Based on sample mask of 1 cubic inch.
Cure Time Test Methods
Cure Time Test Method
960 min Based on sample mask of 1 cubic inch.
960 min
60 min
30 min
15 min
7 min
5.00 min
Linear Shrinkage Test Methods
Linear Shrinkage Test Method
0.10 % After 7 days
Set Time Test Methods
Set Time Set Temperature
30 min 65°C
Viscosity Test Methods
Viscosity Test Method Temperature
90,000 cPs Brookfield Viscometer Model HAF, spindle #6 at 5 rpm. 25°C
Tensile Strength Test Methods
Tensile Strength Cure Time Cure Temperature Test Method
650 psi 1,440 min 25°C Based on sample thickness of 125 mils, cured 24 hours at 77°F (25°C).
Tear Strength Test Methods
Tear Strength Cure Time Cure Temperature Test Method
90 (ppi) 1,440 min 25°C Based on sample thickness of 125 mils, cured 24 hours at 77°F (25°C)
Tear Resistance
Elongation Test Methods
Elongation Test Method
3 % Based on sample thickness of 125 mils, cured 24 hours at 77°F (25°C).
Shore A Hardness Test Methods
Shore A Hardness Shore Hardness Test Method Hardness Temperature
59 Hardness/Durometer Test Method 25°C
Specific Gravity Test Methods
Specific Gravity Temperature Test Method
1.290 25°C Based on sample thickness of 125 mils, cured 24 hours at 77°F (25°C).