this injection blow molding method has special provision for maintaining the plastic of a parison on a core rod at the orientation temperature of the plastic ; and stretching the plastic of the parison lengthwise of the core rod for orientation in the direction of one axis without any substantial increase in the diameter of the parison . after this orientation in one axis , the temperature is controlled to maintain an orientation temperature , and the plastic of the parison is then blown to a larger diameter so as to obtain orientation in another axis for &# 34 ; bi - axial orientation &# 34 ;. the core rod is covered by an elastic balloon , and provision is made for obtaining flow of the plastic on the core rod lengthwise of the rod during the first orientation operation .