 One of the main differences between crazing and shear banding, is that crazing occurs with an increase in volume, which shear banding does not.This means that under compression, many of these brittle, amorphous polymers will shear band rather than craze, as there is a contraction of volume instead of an increase.In addition, when crazing occurs, one will typically not observe "necking," or concentration of force upon one spot in a material.