Welcome to Imerys Performance Minerals

Calcined Clay

Calcined Clay

Imerys calcined clays are structured clays that are formed by treating select hydrous clay feed at high temperature to form agglomerates that have a controlled pore structure that maximizes light scattering. Calcined clay is generally used as a cost-effective opacifier and high light scatter pigment that provides excellent fiber coverage and bulk to the coating layer. It has been successfully used for several decades as a TiO2 extender.

Filling applications

In filling applications, Imerys calcined clays improve:

  • Print appearance
  • Strike through
  • Brightness
  • Opacity

Coating pigment

Used as a coating pigment, Imerys calcined clays improve:

  • Coverage
  • Absorbency
  • Print properties


  • Specialty papers
  • Coated mechanical and coated wood-free
  • Coated cartonboard
  • White top and mottled linerboard
  • Uncoated freesheet

Imerys calcined clay ranges include:

  • Alphatex
    Alphatex is a high brightness, calcined clay used for coating and filling applications in paper and board where high brightness and opacity are required. It is made via a precisely controlled thermal process using a select kaolin feed. The resulting product has a controlled pore structure that maximizes light scattering.
  • Therma-Print
    Therma-Print is a calcined clay, designed to provide the right coating and surface structure for thermal transfer and thermally activated coated printing grades. Therma-Print improves coverage, absorbency and print properties.
  • Opacitex
    Opacitex is a calcined kaolin, that has outstanding opacifying qualities and very low density. It can easily replace titanium dioxide, which is toxic, in decorative laminates.

Slurry and dry bulk form

Imerys calcined clays are available in slurry or dry bulk form that readily mixes in water to form a stable slurry. It is added along with other mineral coating formulation ingredients.


We offer a full range of bespoke formulation and technical and process support services to help you match the right mineral grade to your application requirement.

Please contact us. We will be only too happy to help

Contact us Contact

Paper & Board