GB1019415A - Process for finishing float glass - Google Patents

Abstract

<PICT:1019415/C1/1> Float glass is finished by dissolving at least a portion of the surface which was in contact with supporting liquid. The dissolution reagent may be aqueous hydrofluoric acid with or without fluorosilicic acid. The total concentration of these acids should not exceed 50% by weight of the solution. The solution may contain tin, dissolved from the glass, in amounts from above 0.05 to below 5% by weight. Exemplified temperatures of the reagent solution are 70 DEG F. and 120 DEG F. Treatment is preferably terminated before a depth of 3 microns of the surface glass has been removed. The glass may be supported during treatment on rollers which may be e.g. of rubber. In the Figure is shown a portion 1 of a continuous cooled and washed float glass ribbon from the float tank, the float surface being the underside. Acid solution is fed through 5 to basin 4 having inner rim 6 the inner perimeter of which defines an inner tank, which may be wider or narrower than the glass ribbon. The solution overflows from the inner tank between the glass and rim 6 into gutter 7, so that the entire lower surface of the glass ribbon over the inner tank remains in contact with the liquid. The reagent solution is subsequently removed from the glass by squeegee 11 and water spray 12, and wash water is removed by squeegees 13 and 14. The resultant surface is more readily polished by abrasion than the original float surface, and the treated glass on bending is free from iridescent defect.