Molecular Memory. The surface metal of a struck piece has a tendency to return minutely to its original configuration before it was struck; also called creep or drift. It is imperceptible to the human eye, but can be observed under magnification. This striking problem is cured, somewhat, by a longer extrusion dwell in the press cycle to prevent the metal from springing back while the die is still in the most extended position. Also, of course, it is eliminated by repeated impressions as in multiple striking.