One of my regular stops among online message boards is the Coin Community Forum. Every so often a coin turns up that proves to be a real head-scratcher for its members.
On March 12 of this year, dedicated roll-searcher Steve Young posted photos of a 1998 Lincoln cent showing a second set of letters on the reverse face (www.coincommunity.com/forum/topic.asp?TOPIC_ID=172406). The outer portions of the letters E CE of ONE CENT can be seen below the normal letters and just inside the design rim.
Speculation ran riot as to the cause. I asked Steve to send the coin to me for a closer look. Within minutes I knew I was looking at an error combination I hadn’t seen before, although the constituent errors were quite familiar to me.
The extra letters are die-struck and are arranged along the top of a thin crescent that is elevated above the field but that lies below the level of the design rim. The crescent extends from 4:00 to 7:00, with its widest portion at around 6:00. The normal letters NE CEN are truncated where they meet the internal margin of the crescent, which I quickly recognized as a die attrition error.
This form of peripheral die damage/die loss occurs when the hammer die is temporarily misaligned. While in this position, the die smacks repeatedly against the beveled entrance to the collar. This gradually wears away the outer margin of the field portion of the die face (and sometimes the rim gutter as well). After the die returns to center, every coin it strikes carries a featureless crescent where the die face has been removed.
A typical example of a die attrition error is seen on the illustrated 1983 Lincoln cent. The featureless crescent has invaded the design, leaving the letters of IN GOD truncated. Other die attrition errors can be seen in columns dated Jan. 4, 2010, and Aug. 8 and Dec. 24, 2012.
It is safe to assume that the reverse die that struck this 1998 Lincoln cent functioned as the hammer die. Die attrition errors have only been found on the face struck by the hammer die and there’s little opportunity for such an error to develop on the anvil die. While a conventional die setup (obverse die as hammer die) still dominated in 1998, the use of inverted dies (reverse die as hammer die) was by no means rare.
Effective striking pressure was reduced opposite the deficit in the reverse die face, leaving the obverse letters WE TR a tad weak.
Although it had returned to center, the hammer die that struck the 1998 cent remained unstable. After it struck the planchet represented by Young’s coin, the hammer die bounced up, shifted toward the south, and landed lightly on the featureless crescent. That moment of light contact produced the second set of letters. These added elements show the same damage/truncation as the normal letters.
The extra letters represent an extreme form of machine doubling that is most closely related to rim-restricted design duplication (RRDD). In RRDD, a high-bouncing hammer die lands lightly on the design rim, leaving an extra set of design elements. An example can be seen here on a 1994 Lincoln cent, while other examples can be seen in columns dated in Feb. 22, May 24, and Dec. 6, 2010; Aug. 22, 2011; and Oct. 21 and Dec. 30, 2013. In the case of this 1998 cent, the die didn’t travel as far as the design rim. Its lateral excursion and eventual descent carried it only as far as the elevated crescent, which still represented a vulnerable target for the descending hammer die.