This test method covers the determination of the comparative tensile properties of glass fiber strands , yarns , and rovings in the form of impregnated rod test specimens when tested under defined conditions of pretreatment , temperature , humidity , and tension testing machine speed . This test method is applicable to continuous filament , glass fiber materials that have been coated with a resin compatible sizing . This method is intended for use in quality control and R & D , and should not be used to develop composites design data.