Saprolithes are special clays from primary deposits comparable to kaolin but with different mineralogical
composition. The most important characteristic of Saprolithes from the Westerwald region is an amount of
roughly 50 % mica minerals. Processing such Saprolithes by dry processing enables the production of economic
fillers for a wide range of applications. The Stephan Schmidt Group produces Saprolithe fillers as well as plastic
clay fillers under the brand Capsil®.
Blending Saprolithes with different raw material – especially amendment of high plastic clays – leads to
different physical properties of the Capsil® fillers. Subsequently it is possible to produce fillers with more or
less reinforcing characteristics. Different grades of grinding are possible as well. First results of Capsil® fillers
in rubber applications are given in the presentation.