Question: Occasionally I read in coin descriptions about “lapping” or “lapping lines.” Can you explain these? – M.T.
Answer: Lapping is one of several names, including die polishing and die filing, for the fine abrading used to finish a die when it is first produced or, more frequently, repaired. At the time of production, a die usually has some inherent flaws from nicks and scratches to swelling and cracks. The tiny flaws, like a random scratch in the dies, may usually be corrected by minor polishing with a fine grain abrasive such as steel wool or emery. The fine markings etched on the die by the abrasive are called “die finish lines” or “lapping lines,” though usually “die finish” refers to a finer grain than “lapping lines,” which are more likely caused by a file or something of heavier grain. The abrasives may also be used to smooth out rust or damage on a well-used die, or to smooth over a small crack. Occasionally, dies will be “lapped,” thus effacing details, and re-engraved or repunched. Misplaced dates and the like show only light remnants of the errantly placed punch because most details were simply “lapped” away. This term is most often used in reference to mid 19th-century coinage it seems, though you can undoubtedly see fine lines of “die polish” or “die finish” on coins in your pocket change!