P 2479 (OTTO) Potassium silicofluoride, 98% Cas 16871-90-2 - used to manufacture opalescent glass. P 2479 (OTTO) Potassium silicofluoride, 98% Cas 16871-90-2 - used in the manufacture of porcelain and also for the preservation of wood. It is involved in the production of ceramics , aluminum and magnesium melts and also serves as an intermediate in the production of optical glass.