High Strength 2

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High Strength 2 is a tin-based silicone mold making rubber with high tear strength and is great for making all types of molds – it’s soft enough for 1-piece molds with undercuts and strong enough for 2-piece molds with secure alignment.

  • Doesn’t require degassing, but recommend when possible
  • Use Rubber to Rubber mold release or petroleum jelly when making 2-piece molds

Prior to using product, please read all Technical Data, Safety Data, and Instruction sheets linked below.


Technical Specifications

High Strength 2
Mix Ratio:
10:1 by weight
Pot Life:
45 minutes
Demold Time (100 gram mass):
12-18 hours
Specific Gravity:
Mixed Viscosity (cps):
18,000 at 130º F
Shore Hardness (ASTM D2240):
20-23 A
Tear Strength (ppi):
Linear Shrinkage:
Elongation (in./in.):
Tensile Strength (ASTM D638, psi):
Temperature Resistance:
-67º to 395º F


  • 2

    Posted by Jim Brokaw on May 9th 2020

    I have been making RTV molds since 1972. Recently I have been using HS2 to make multi piece molds of small (10mm) model buildings. I use a triple beam balance to weigh the base and catalyst. I mix a small quantity and brush it over the mold so there won't be any bubbles on the surface of the model, then pour a thin stream and blow on the rubber to burst any bubbles as I pour the rest of the mold. I pour 20 to 50 grams at a time. The last lot of RTV set up so fast that the working time was reduced to no more than 7 minutes after mixing, making it hard to remove the bubbles or even pour the rubber.