For Type CP test pieces, the thickness of the tear path may be measured one of two ways: (1) the total thickness of the test piece along the groove is measured at three places, averaged,
and 3.60 mm is subtracted to account for the mold insert sections that form the groove; or (2) the torn surface is examined with a small binocular magnifier with a graduated reticle and the thickness measured and averaged. The second method is more accurate, but the two methods have been found to agree to within about 5 %. For routine work the first method has been found to be satisfactory. Based on the mold dimensions, the thickness is approximately between 1.70 and 1.80 mm.