Dow Silastic J RTV Silicone Rubber
Brand Silastic Chemical Resistance Excellent Application Type Mold-Making 1 Part or 2 Part 2-Part Material Form Liquid Manufacturer Dow Chemistry Silicone rubber Cure Method Base/curing agent, Heat Cure Temperature (°C) 20 to 25, 23, 23 Cure Time (min) 1,080 to 1,440, 1,440 Viscosity (cPs) 85000 (mPa.s), Pourable High Temperature Resistance (°C) High, 200 Density (g/cm³) 0.001
Technical Data for Dow Silastic J RTV Silicone Rubber
Cure Temperature (°C) 20 to 25, 23, 23 Test Method Cure Time (min) 1,080 to 1,440, 1,440 Test Method Viscosity (cPs) 85000 (mPa.s), Pourable Test Method Linear Shrinkage (%) 0.10 Test Method Work / Pot Time (min) 120 to 80 Test Method Mix Ratio 10:1 (by volume), 100:10 (by weight)
General Bond Strength (psi) High Tear Strength (piw) 15 (kN/m) Test Method Tensile Strength (psi) 5.5 (Mpa) Test Method
High Temperature Resistance (°C) High, 200
Shore A Hardness 56, High Test Method Elongation (%) 3 Test Method Flexibility Flexible
Flash Point (°F) 213.8 Density (g/cm³) 0.001 Test Method
Shelf Life Details When stored at or below 43°C (109.4°F) in the original unopened containers, SILASTIC J Base and SILASTIC J Curing Agent have a usable life of 12 months from the date of production. Shelf Life Type from the date of production Shelf Life (mon) 12
Not Good For
Don't Use For food molding, dental, human skin molding applications.
Best Practices for Dow Silastic J RTV Silicone Rubber
The surface of the original should be clean and free of loose material. If necessary, and in particular with porous substrates, use a suitable release agent such as petroleum jelly or PTFE.
Pour the mixed base and curing agent as soon as possible onto the original, avoiding air entrapment.
Thoroughly stir SILASTIC J Curing Agent before use. Weigh 100 parts of SILASTIC J Base and 10 parts of SILASTIC J Curing Agent (see handling precautions) in a clean container, then mix together until the curing agent is completely dispersed in the base. Hand or mechanical mixing can be used, but do not mix for an extended period of time or allow the temperature to exceed 35°C (95°F). Mix sufficiently small quantities to ensure thorough mixing of base and curing agent.
It is strongly recommended that entrapped air be removed in a vacuum chamber, allowing the mix to completely expand and then collapse. After a further 1-2 minutes under vacuum, the mix should be inspected and if free of air bubbles, can then be used. A volume increase of 3-5 times will occur on vacuum de-airing the mixture, so a suitably large container should be chosen.
Note: If no vacuum de-airing equipment is available, air entrapment can be minimized by mixing a small quantity of base and curing agent, then using a brush, painting the original with a 1-2mm layer. Leave at room temperature until the surface is bubble free and the layer has begun to cure. Mix a further quantity of base and curing agent and proceed as follows to produce a final mold.
The catalyzed material will cure to a flexible rubber within 18-24 hours at room temperature (2224° C/ 71.675.2° F) and the mold can then be removed. If the working temperature is significantly lower, the cure time will be longer. Heat accelerating the cure is possible, but this will produce some apparent shrinkage of the mold due to differences in volume contraction on cooling between the silicone rubber and the original. The higher the curing temperature, the greater the likely differences in dimensions. As a guide, a 5mm section of SILASTIC J will heat cure in 30 minutes at 65°C (149°F) or in 12 minutes at 100°C (212°F) once the material has reached this temperature.
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Cure Temperature Test Methods
|Cure Temperature||Cure Time Test Method|
|20 to 25°C|
|23°C||Cured for 24 hours at 23°C (73.4°F)|
Cure Time Test Methods
|Cure Time||Test Method|
|1,080 to 1,440 min|
|1,440 min||Cured for 24 hours at 23°C (73.4°F)|
Linear Shrinkage Test Methods
|Linear Shrinkage||Test Method||Temp|
|0.10 %||Cured for 24 hours at 23°C (73.4°F)||23°C|
Viscosity Test Methods
|85000 (mPa.s)||Base and Curing Agent mixture (100:10 by weight)|
Work / Pot Time Test Methods
|Work / Pot Time||Temperature|
|120 to 80 min||23°C|
Tear Strength Test Methods
|Tear Strength||Cure Time||Cure Temperature|
|15 (kN/m)||1,440 min||23°C|
Tensile Strength Test Methods
|Tensile Strength||Cure Time||Cure Temperature|
|5.5 (Mpa)||1,440 min||23°C|
Elongation Test Methods
|3 %||Cured for 24 hours at 23°C (73.4°F)|
Shore A Hardness Test Methods
|Shore A Hardness||Shore Hardness Test Method||Hardness Temperature|
|56||Cured for 24 hours at 23°C (73.4°F)||23°C|
Density Test Methods
|0.001 g/cm³||23°C||Cured for 24 hours at 23°C (73.4°F)|