Dow Silastic M-2 RTV Silicone Rubber
Brand Silastic Application Type Mold-Making 1 Part or 2 Part 2 Part Material Form Liquid Industry Architectural, Production tooling, Architectural components Manufacturer Dow Chemistry Silicone rubber, Urethane foams Cure Method Base/Curing agent Cure Temperature (°C) 20 to 25, 25 Cure Time (min) Fast, 1,440, 240 to 300 Viscosity (cPs) 66,000, Pourable High Temperature Resistance (°C) Very high Other Resistance Inhibition
Technical Data for Dow Silastic M-2 RTV Silicone Rubber
- Casting / Moldmaking - Mold-Making
1 Part or 2 Part
- 1 Part or 2 Part - 2 Part
- Part A Name - Base
- Part B Name - Curing Agent
- 2-Part Cure - Base/Curing agent
Cure Temperature (°C) 20 to 25, 25 Cure Time (min) Fast, 1,440, 240 to 300 Viscosity (cPs) 66,000, Pourable Test Method Linear Shrinkage (%) 0.10 Test Method Work / Pot Time (min) 90 Mix Ratio 10:1 (by volume), 100:10 (by weight)
Tear Strength (piw) Good, 85 (ppi) Test Method Tensile Strength (psi) 700 Test Method
High Temperature Resistance (°C) Very high Other Resistance Inhibition
Shore A Hardness High, 59 Test Method Elongation (%) 2 Test Method Flexibility Flexible
Specific Gravity 1.290 Test Method Flash Point (°F) 212.0
Shelf Life Details When stored at or below 32°C (90°F) in original unopened containers, Silastic M-2 RTV Silicone Rubber has a shelf life of 12 months from date of manufacture. Refer to product packaging for “Use By” date., Both base and curing agent can be sensitive to moisture and contamination. Ensure containers are tightly closed after use. Shelf Life Type from date of manufacture Shelf Life (mon) 12
Best Practices for Dow Silastic M-2 RTV Silicone Rubber
Certain contaminants found in moldmaking operations can prevent Silastic M-2 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 or cardboard, foil, wood, or other material. There should be approximately (0.95-cm) 3/8- 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 combining five percent petroleum jelly and 95 percent solvent. Combine the materials and let stand overnight – then shake by hand to provide a good mix.
Pressure casting may be substituted with equal success.
Pour the mixed base and curing agent onto the master, avoiding air entrapment.
Weigh out 100 parts of Silastic M-2 RTV Silicone Rubber base and 10 parts of curing agent in a clean container. Mix until the curing agent is completely dispersed in the base and a uniform color is obtained.
Entrapped air should be removed in a vacuum chamber, allowing the mixture to completely expand and then collapse. After an additional three minutes of vacuum, the mix should be inspected and can be used if free of air bubbles. A volume increase of three to four times will occur on vacuum deairing of the mixture, so a suitably large container should be chosen.
The catalyzed mixture will typically cure to a flexible rubber within four to five hours at room temperature, at which time the part can be demolded. Heat accelerating the cure is possible, but some physical property changes, such as increased durometer hardness, will occur.
NOTE: Above room temperature, the working time for Silastic M-2 RTV Silicone Rubber is substantially decreased. Due to this decrease in working time, automatic dispensing equipment is recommended.
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Linear Shrinkage Test Methods
|Linear Shrinkage||Test Method||Temp|
|0.10 %||Cured 24 hours at 25°C (77°F).||25°C|
Viscosity Test Methods
|66,000 cPs||As Mixed – 100 Parts Base to 10 Parts Curing Agent by Weight|
Tensile Strength Test Methods
|Tensile Strength||Cure Time||Cure Temperature||Test Method|
|700 psi||1,440 min||25°C||Cured 24 hours at 77°F (25°C).|
Tear Strength Test Methods
|Tear Strength||Cure Time||Cure Temperature||Test Method|
|85 (ppi)||1,440 min||25°C||Die B, cured 24 hours at 77°F (25°C).|
Elongation Test Methods
|2 %||Cured 24 hours at 25°C (77°F).|
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||Test Method|
|1.290||100 Parts Base to 10 Parts Curing Agent by Weight|