The first theory concerning the polishing of glass, which viewed polishing as an extension of the grinding process with finer abrasives, and the flow theory of Beilby, both stipulate purely hypothetically that the polishing grains should have a very high hardness. This hypothesis was strongly supported by Smekal and Bruche in the 40s and 50s and by other scientists in future years and has remained virtually universally accepted to this day. The results of investigations of this author show that first, extra lattice defects in the crystalline oxides used as polishing agents are the primary characteristics that are responsible for the gripping of the grains during polishing and second, the hardness of the grains of the polishing agent must be lower than that of the material which is being polished. By and large these results have been ignored in the literature.
