Abstract: A gradient photochromic ophthalmic lens blank is produced by heat treating an ophthalmic lens blank composed of potentially photochromic glass at a temperature sufficient to develop photochromic properties therein, while maintaining in proximity to a portion of the lens blank a metal heat sink with a specified heat absorbing capacity. The metal heat sink acts to provide a temperature gradient across the ophthalmic lens blank during heating, which gradient is effective to provide a gradient in photochromic properties thereacross.

Abstract: The present invention relates to a process and apparatus useful therein for steam hydrating alkali silicate glass materials and subsequently extruding the hydrated material. There need be no moving parts in the hydration apparatus since the process can utilize the pressure of steam to both hydrate the glass and extrude it from the hydration chamber. The process permits the formation of solid extrusions or foam extrusions.

Abstract: A method of heat treating a plurality of geometrically congruent and flat lens blanks made from a phototropic glass, such heat treating being performed for development of the phototropic properties thereof. A plurality of lens blanks are formed into a stack by alternately positioning and clamping similar areas between the flat surfaces of two flat, annular, spacer members. The stack is then rotated about the longitudinal axis oriented in a substantially horizontal position while evenly heating the lens blanks to the phototropic development temperature of the glass. The stack of blanks is then vertically positioned while continuing the heating thereof and part of each of the blanks sags into the hollow of the spacer member therebelow to form such part of each blank into a curved configuration for an eyeglass lens.