Dow Silastic L RTV Silicone Rubber

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Description for Dow Silastic L RTV Silicone Rubber

Low durometer, soft and more flexible, good elongation.

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

Best Practices for Dow Silastic L RTV Silicone Rubber

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Technical Data for Dow Silastic L RTV Silicone Rubber

*See Terms of Use Below

Overview

Application Type
- Casting / Moldmaking - Mold-Making
- Pottant / Encapsulant - Pot, Encapsulate
1 Part or 2 Part
- 2-Part
Material Form
- Liquid
Chemistry
- Silicone - Silicone rubber
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.
Comparable Materials for Dow Silastic L RTV Silicone Rubber

*See Terms of Use Below

Spec Engine^® Results
- Semicosil 949 UV A/B(Wacker)
  Wacker Semicosil 949 UV A/B is a 2-Part 2-Part Cure Silicone Rubber Liquid used to Pot and Encapsulate Thermoplastics and Pins
- RTV-4130-J Kit(Dow)
  • Outstanding release properties • High durometer hardness • Very low shrinkage and good dimensional stability • Good cut-growth resistance • Can be used for high temperature casting applications • Room temperature cure within 24 hours • Heat-accelerable cure
- RTV60(Momentive)
  Momentive RTV60 is a 2-Part 2- Part Cure Silicone Rubber Liquid used to Cast and Mold
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