GB695233A - Improvements in or relating to non-reflective television tube face plates - Google Patents

Abstract

695,233. Modifying surface reflection. DEARBORN GLASS CO. April 9, 1951 [May 18, 1950], No. 8224/51. Class 97 (i). [Also in Group XL (a)] Reflection from the glass screen of a television tube is reduced by cleaning and etching both surfaces of said screen with a first mildly acidic glass-etching bath, removing the screen from said bath and introducing it while still wet into a second supersaturated heated glassattacking acidic bath, removing the screen from the second bath, rendering the second acidic bath solution on said screen inactive and cleaning it of all residue, submerging the screen in a third bath of intermediate strength for a time greater than the combined bath times of the screen in the first two baths, and removing the screen from the third bath and rendering inactive the acid remaining thereon. The first bath may comprise an aqueous solution containing from 6-10 per cent hydrofluoric acid by weight and the screen may lie therein for a time varying between 20 seconds and 3 minutes. The second bath is at room temperature and comprises an aqueous solution of hydrofluoric acid, ammonium bifluoride, sodium chloride and diethylene glycol and the screen is immersed therein for about two minutes. The third bath is an aqueous solution of hydrofluoric acid and the screen is immersed therein for 4 to 6 minutes.