Dow Silastic L RTV Silicone Rubber

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

    Low durometer, soft and more flexible, good elongation.

    *See Terms of Use Below

    Brand Silastic
    Application Type Mold-Making, Pot, Encapsulate
    1 Part or 2 Part 2 Part
    Material Form Liquid
    Manufacturer Dow
    Chemistry Silicone rubber
    Cure Method Base/Curing agent
    Cure Temperature (°C) 25
    Cure Time (min) 1,440
    Viscosity (cPs) 92500 (mPa-s), Pourable
    Color Green
    Key Specifications FDA (U.S. Food & Drug Administration) and/or CFIA (Canadian Food Inspection Agency): FDA 21 CFR 177.2600
  • Technical Data for Dow Silastic L RTV Silicone Rubber

    Overview
    • 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
    • Chemistry
    • Cure Method
      • 2-Part Cure - Base/Curing agent
    • Color
      • Green
    • Key Specifications
      • FDA (U.S. Food & Drug Administration) and/or CFIA (Canadian Food Inspection Agency): 177.2600 - FDA 21 CFR 177.2600
    • Brand
      • Silastic
    Specifications
    Cure Specs
    Cure Temperature (°C) 25 Test Method
    Cure Time (min) 1,440 Test Method
    Viscosity (cPs) 92500 (mPa-s), Pourable Test Method
    Work / Pot Time (min) 150 Test Method
    Mix Ratio 10:1 (by volume), 10:1 (by weight)
    Bond Strength
    General Bond Strength (psi) High
    Tear Strength (piw) 60 (ppi) Test Method
    Tensile Strength (psi) 550 Test Method
    Hardness
    Shore A Hardness 34, 35 Test Method
    Elongation (%) 350, High, Superior Test Method
    Flexibility Excellent
    Modulus (psi) Low
    Other Properties
    Specific Gravity 1.280 Test Method
    Flash Point (°F) 213.8
    Business Information
    Shelf Life Details Silastic L RTV Silicone Rubber and its curing agent should be stored in closed containers at or below room temperature. The materials have a usable 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 L RTV Silicone Rubber

    *See Terms of Use Below

    1. Surface Preparation

      Certain contaminants sometimes used in moldmaking operations can prevent Silastic L 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 1/4-inch clearance on all sides and over the top of the pattern. The pattern 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 making a 5 percent solution of petroleum jelly in a suitable solvent. Either VM&P naphtha or mineral spirits can be used.

    2. Mixing

      Silastic L RTV Silicone Rubber base and its curing agent are produced in matched lots

      the two parts should be used in the kit form, as supplied. For the best curing results, use metal cans, clean glassware or unwaxed paper containers for mixing the base and curing agent. Silastic L RTV Silicone Rubber curing agent should be mixed into the base material just before use (with either manual or mechanical stirring) in the amount of one part curing agent to ten parts base by weight.

    3. Deairing/Degassing

      Inclusion of air during mixing may cause voids 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 four to five 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 L RTV Silicone Rubber occurs by a reaction between the base polymer and the curing agent. This 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. The rate at which sections will set up depends on the size and shape of the piece. Vulcanization will not be accelerated at the center of the piece until the entire mass has reached the elevated temperature.

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    *See Terms of Use Below

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
25°C CTM 0092A, Based on sample mass of one cubic inch.
Cure Time Test Methods
Cure Time Test Method
1,440 min CTM 0092A, Based on sample mass of one cubic inch.
Viscosity Test Methods
Viscosity Test Method Temperature
92500 (mPa-s) CTM 0050, Brookfield Viscometer Model HAF, spindle #6 at 5 rpm. 25°C
Pourable
Work / Pot Time Test Methods
Work / Pot Time Test Method Temperature
150 min CTM 0092A, Time required to become nonflowable. 25°C
Tear Strength Test Methods
Tear Strength Cure Time Cure Temperature Test Method
60 (ppi) 1,440 min 25°C CTM 0159A
Tensile Strength Test Methods
Tensile Strength Cure Time Cure Temperature Test Method
550 psi 1,440 min 25°C CTM 0137A, Based on sample thickness of 125 mils, cured 24 hours at 25°C (77°F)
Elongation Test Methods
Elongation Test Method
350 % CTM 0137A, Based on sample thickness of 125 mils, cured 24 hours at 25°C (77° F).
High Elongation Test Method
Superior Elongation Test Method
Shore A Hardness Test Methods
Shore A Hardness Shore Hardness Test Method Hardness Temperature
34 Hardness/Durometer Test Method 25°C
35 CTM 0099, Based on sample thickness of 125 mils, cured 24 hours at 25°C (77° F).
Specific Gravity Test Methods
Specific Gravity Temperature Test Method
1.280 25°C CTM 0022