Aktifit is an activated Silfit Z 91 produced by modifying the surface with special functional groups. The by-products split off during the treatment reaction are largely removed during the production process which firmly attaches the functional groups to the filler surface. This helps minimize undesirable side effects, as they are potentially encountered with in-situ mixing (direct addition of additives to the compound).

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.