Lays down a characteristic temperature at which cracks are produced in film or thin sheeting, as a guide to its low-temperature performance. The maximum thickness depends on the stiffness of the material and the ability of the hammer to flatten the loop of material at the test temperature, but is about 1 mm for flexible sheeting. It is known that unsatisfactory results are sometimes obtained with thin polished plasticized PVC sheeting and PVC sheeting having a low plasticizer content.