White fused alumina: high hardness and transparence

White fused alumina is an industrial product. It is melted of high quality white fused alumina in an electric arc. White fused alumina consists of about 99 % α-aluminium oxide. The outstanding property of white fused alumina is a high hardness and transparency. Only diamonds are tougher. This high hardness is a challenge for every grinding technology. Our micronized white fused alumina flours SEPASIL® are characterized by a narrow grain size distribution. Another refining step is the surface-treatment with silanes or silane-based substances which can be adjusted to the respective application.


  • depending on processing: the grain shape is round or splintered

  • high hardness of 9 (Mohs)

  • density of 3.95 g/cm³

  • chemically inert

  • high chemical resistance

  • narrow grain size distribution

  • transparent performance in many binding systems

Key applications:

  • abrasion-resistant wood and decorative coatings

  • laminates

  • casting resin systems and high voltage isolators

High Performance Fillers based on white fused alumina: