NNP

Sunken Die.  A die deteriorated by a portion of its striking surface being compacted and recessed. The sinking is due to long use, poor quality steel and improper hardening. It is never known in advance when a die will sink, if it will sink, or how severe the form of sinking will be. It is a very gradual process and usually occurs in dies after long time, particularly over intermittent periods of use. It is characteristic of an old die.

Pieces struck from a sunken die obviously will exhibit the sunken condition. The effect is quite slight in the beginning of the die's deterioration, gradually worsening with continued use. If the sinking is greatest in the center and grading to the edge the sunken condition of the die will result in a domed effect on the struck piece. The dome increases with subsequent strikes as the continued force of striking takes its toll on the impaired die. All relief and detail is affected rising from the domed table or field of the struck piece. More likely the sinking is not uniform and the effect is more wavy or buckled, as a portion of the die's surface sinks faster than an adjacent area.

Sunken dies are rare in modern times – from using higher quality steel from which the dies are cut, better heat treating methods and there are fewer instances of dies being used over long periods of time. No die, however, is immune from potential sinking but better tool steel is worth the extra cost to prevent this.

Sunken coins.  A vivid example of sunken coin dies exists in some early coins struck by the fledgling U.S. Mint. The cents and half cents of 1793, the first struck from dies made by Henry Voigt who was inexperienced in heat treating the dies to prohibit this condition. Thus fresh dies deteriorated rapidly by sinking and cracking before long runs could be struck. Die life significantly improved once Adam Eckfeldt was hired as the Die  Forger and Turner in 1795, first on contract, then as a position. Dies continue to sink and crack today, although the problem is much reduced with new alloy steels.

Sunken medals.  Historically one series of medals exhibits sinking moreso than any other. Papal medals have been issued over hundreds of years. Two and three-hundred year-old dies were still employed to strike medals – as long as they had not broken – because there was sustained demand for early papal medals. The original steel from which the dies were made was not the best, storage conditions may not have been the ideal, and intermittent use took its toll. The dies became sunken over the years as evident in the deficient medals with uneven and buckled surfaces we observe today.

References:                                                                                                                                    

NC6 {1988} Breen, p 181.

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