Silicones for microfusion molds

High-strength silicones for the lost wax method

Coniex has developed a wide range of silicones for microfusion, which are marketed under the CASTEX line. We offer 5 different types of silicone for microfusion, which are divided according to several characteristics such as vulcanization temperature, reduction percentage, hardness and tear resistance. These silicones are ideal for molding by the lost wax method.

CASTEX microfusion silicones have a high resistance and have been specially designed for the manufacture of molds for microfusion by the lost wax method, both for jewelry and costume jewelry, as well as for industrial applications in steel.

The CASTEX range of silicones offers excellent performance in the manufacture of molds for microfusion models, while providing the most faithful copies of the original that can be found on the market.

CASTEX microfusion silicones allow the combination of different hardnesses in the same mold. Moreover, thanks to their excellent mechanical characteristics, they can be used with talc, thus avoiding cutting, or opened with a scalpel in the traditional way.

Once the mold has been made, other subsequent processes such as cutting, access to the model and wax injection are carried out more easily and conveniently than with rubber molds. In addition, wax injection is carried out more smoothly, since it is not necessary to use talc or silicone spray, if desired, for the wax to circulate correctly in the mold.

Main technical characteristics:

  • All types of hardness, from very low to high.
  • Vulcanization temperature varies between 100° C and 160° C depending on the model.
  • Low shrinkage
  • Glossy type finish
  • Variable hardness from high to very high
  • Variable sheet size depending on the model

In addition, our range of CASTEX hotmelt silicones offers the following properties:

Surface finish:

  • A shiny surface on your molds will make you get better and shinier wax parts with excellent results.
  • No need for release agent or talc: The high elasticity of CASTEX Microfusion Silicone allows easy and fast demolding.
  • High tear resistance: With CASTEX, you will be able to make the most difficult cuts without any problems.
  • Ease of molding: Due to its low raw viscosity, it allows you to embed the part and place it in the mold by simply pressing with your fingers. This is a significant time saver.
  • Perfect state of conservation: Molds made with Microfusion Silicone CASTEX are perfectly preserved for many years.
  • Shrinkage: The shrinkage of CASTEX SM40/120 andSM43/120 is less than 1.5%, while the shrinkage of SM 45 and SM50 is around 2.8%.

Range of CASTEX microfusion silicones

SM 40/100

  • Viscosity: Very Low
  • Hardness: 40 Sh
  • Lengthening: >650
  • Tear resistance: Very High
  • Contraction L %: 1.4
  • Vulcanization temp. 100ºC 212ºF

SM 40/120

  • Viscosity: Low
  • Hardness: 40 Sh
  • Lengthening: High
  • Tear resistance: High
  • Contraction L %: 1.8
  • Vulcanizing temp. 120ºC 248ºF

SM 43/120

  • Viscosity: Low
  • Final hardness: Low
  • Lengthening: High
  • Tear resistance: High
  • Contraction L %: 1.6
  • Vulcanizing temp. 120ºC 248ºF


  • Viscosity: Low
  • Final hardness: Medium
  • Lengthening: High
  • Tear resistance: High
  • Contraction L %: 2.6
  • Vulcanization temp. 160ºC 320ºF


  • Viscosity: Medium
  • Final hardness: High
  • Lengthening: Medium
  • Tear resistance: High
  • Contraction L %: 2.3
  • Vulcanization temp. 160ºC 320ºF