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.

$33.99 - $199.99
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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

More Information

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

See It In Use


  • 5
    First try

    Posted by JW on Oct 7th 2021

    I thought for sure I would do something wrong since this was my first try at making a mold of any kind but I surprised myself or got lucky. I mixed it up then poured into mold box I made then put it in vacuum chamber. I let it rise up then fall and after about 30 seconds cut pump off. I just barely opened valve on chamber and all the air bubbles on top slowly started to dissappear. When vacuum was gone so were the air bubbles. It turned out really nice using vacuum chamber. Now I just have to finish my pressure chamber so I can try out my new mold.

  • 1

    Posted by Brian Maney on Jun 6th 2021

    It says to expect.003 shrinkage. More like 1/8”. Don’t use this if you’re trying to mold something where dimensions are crucial. Also. It says rubber is pink in description.... mine was white. Idk.

  • 5
    Love this stuff...

    Posted by Patrick Goodman on Nov 12th 2020

    We use this High Strength 2 for molding 3D printed parts, so we can cast in resin. The high tear strength is great and you can typically use this for stuff that would typically require a 2 piece mold.

  • 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.