Capping
Capping. A striking error where a piece does not eject but wraps around the die on subsequent strikes. The resulting piece takes the shape of a bottle cap, hence this name. Collectors call this a cap, or capped die. Mint workers prefer the term cupping.
excerpted with permission from
An Encyclopedia of Coin and Medal Technology
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor