Applicable Products: K2139

Television Settling

Potassium Silicate is used as a binder for phosphor particles on the face of black and white television picture tubes. The Silicate micelles bear strong negative surface charges and are highly adsorbed on both the glass and the phosphor. The two repel each other until an electrolyte such as barium acetate is added. Then a slow developing polymerization with the silica cements the phosphors to the face of the tube. Unlike Sodium Silicate, Potassium Silicate does not affect the emission.

Traces of certain metals are detrimental and, of course, the ratio of alkali to silica and the concentration of solids must be held between narrow limits. Potassium products for cathode ray tube production are of special purity and uniformity. Spectrographic analyses show the absence of copper, nickel and other elements, which cause screen contamination.