Method for making polarizing glasses through extrusion

A method for making glass strip exhibiting polarizing properties from silver-containing glasses characterized as containing particles of metallic silver and/or as being photochromic through the presence of silver halide particles therein selected from the group of AgCl, AgBr, and AgI, said strip having a concavo-convex configuration across the width thereof and a linear curvature therein, which comprises the steps of:

• (a) extruding said glass at an elevated temperature between about the annealing and softening points of the glass at an applied pressure of at least 3000 psi to elongate said metallic silver and/or silver halide particles to an aspect ratio of at least 2:1 and align them in the direction of glass flow, said extrusion being carried out utilizing a die structure having a curved slot orifice;
• (b) passing said glass into a channel having a cross-sectional configuration similar to that of said curved slot orifice and having a bend therein to form a glass strip having a concavo-convex configuration across the width thereof and a linear curvature therein;
• and then
• (c) subjecting said glass strip to conditions sufficient to inhibit respheroidization of the elongated particles.