High Strength 1

(2 reviews) Write a Review

Use High Strength 1, a tin-based silicone mold making rubber, when your mold requires a little more stiffness but still need exceptional tear strength.

  • Doesn’t require degassing, but recommend when possible
  • Great for one- or two-piece molds that require stiff mold properties
  • 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.

$27.50 - $165.50

Technical Specifications

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


  • 2
    This used to be perfect

    Posted by MARY TOTZKE on Sep 14th 2021

    I have been using this product for over 5 years and it's always been perfect. However, the last two batches I received are not the same as usual. I purchased one batch in March 2021 but had to wait a couple of months before I could use it. It was very thick and hard to de-gas. I chalked it up to letting it sit around for too long. Ordered another batch a few weeks ago, and it is even worse! Four of the 11 molds I poured are ruined - and I only get one chance to make a mold. I compared it to my "older" batch, and this recent batch is even thicker. I've made 200+ molds using the product, so it is not operator error. Something is wrong with this product.

  • 4
    High strength mold

    Posted by Dale Fischer on Jul 17th 2021

    The stuff started to kick off faster than I had anticipated it would. So, degassing it did not work the best. Still, it worked out well. Just got to start using it now.