Silfit Z 91 is a naturally occurring conglomerate of corpuscular Neuburg Silica and lamellar kaolinite, which has been subjected to a heat treatment. The components and the thermal process lead to a product that offers special performance benefits as functional filler.

The resulting products have an outstandingly high degree of white and color neutrality. Areas of application include high-voltage cables, light-colored rubber compounds, thermoplastics and as a partial replacement for titanium dioxide, especially in paints and varnishes.

All calcined products have a particle size that approaches that of the uncalcined basic material Sillitin Z 86.

The measuring method for this particle size distribution is based on the Fraunhofer analysis of diffraction spectra.
The analyses were performed with a Matersizer 3000, which is a laser device from Malvern Instruments.

With regard to the CIELAB color values L*, a* and in particular b*, the calcined products are significantly brighter and more color neutral than the classic products Sillitin and Aktisil.