Welcome to Imerys Performance Minerals

Mechanical properties

Mechanical properties Imerys minerals are excellent reinforcement agents improving the mechanical properties of rubber compounds

Imerys kaolins, calcined clays, wollastonite, diatomaceous earth and talc, particularly the finest grades with the highest surface area, are highly effective mechanical reinforcement agents in rubber.

Imerys minerals improve:

  • Shore hardness
  • Tensile strength
  • Elongation
  • Modulus 
  • Compression set
  • Cut and tear resistance
  • Abrasion resistance
  • Crack growth and fatigue resistance
  • Thermal and weather ageing


Imerys calcined clays such as those from our Polestar® and Glomax® ranges are particularly effective for improving all-important compression set in gaskets and seals. 

Our Suprex hydrous clay is an excellent solution for boosting the mechanical performance of rubber hoses for automotive and domestic appliance applications where higher shore hardness is required. Franklin R and Paragon clays are superior choices for semi-reinforcement when intermediate hardness is required.

For more extreme mechanical requirements, surface-treated Mercap, Amlok and Polarite grades are also available, depending on the cure package.


Fine grade wollastonites such as our Wollastocoat® range with their acicular shape provide excellent reinforcement properties and reduced costs in fluoroelastomer (FKM) seals, gaskets, plugs, o-rings and molded applications.

Diatomaceous earth

Natural diatomaceous earths such as our Celtix grades are a great choice for replacing precipitated silica to improve compression set in EPDM.


Microlamellar Mistron®, which has a higher surface area at the same fineness as conventional lamellar talc, improves elastomer chain wetting, providing better reinforcement levels than conventional lamellar talcs. Used as a partial substitution for carbon black, Mistron® improves mechanical properties such as elongation at break and cut and tear resistance of peroxide cured compounds, even at high temperatures.