A lay-flat tubular film of HDPE (High Density Polyethylene) or PP (Polypropylene) is longitudinally stretched near room temperature at a ratio about 3:1, then helically cut e.g. under 45 degrees to form a film oriented on bias. Two such films are continously extrusion laminated with their two directions of orientation crisscrossing. Developments on laboratory and pilot scales, e.g. to optimize the longitudinal stretching, was carried out in Denmark in 1954-63 by O-B R, his employed technicians, and as consultants the Danish engineering company Wolff & Kaaber.
Pioneering work of making the project commercial 1964-68 by the Dutch Van Leer Organisation under the leadership of Mr. Oscar Van Leer (cooperating with O-B R and Wolff & Kaaber).
Van Leers production of the crosslaminate started in 1968 in Essen, Belgium, and Houston, Texas. It still runs successfully (now under new owners). Name of the product is Valeron ®.