Injection blow molding method

A method for producing non-circular plastic bottles by injection blow molding in a non-circular mold having mold walls wherein opposing portions of said mold wall are closer to each other than other opposing portions of said mold walls, including the steps of:

• injection molding a parison of uniform temperature, said parison having a circular outer contour, a bottom, and a said wall wherein opposing portions of the wall of the parison have a greater wall thickness than other opposing portions of the parison wall, said thicker wall portions having a greater capacity to store heat than said thinner wall portions;
• positioning the parison in said blow mold so that upon expansion of the parison during blow molding, the opposing portions of the parison having greater wall thickness will contact the opposing portions of the blow mold wall closest to each other before the opposing portions of the parison having a lesser wall thickness contact the remainder of the blow mold walls;
• and
• blowing the parison so positioned into a finished bottle whereby, the thicker wall portions of the parison having more heat than the thinner wall portions will permit the remainder of the parison to extend into the remainder of the blow mold and contact the remainder of the blow mold walls to form a finished bottle having a relatively uniform wall thickness.