CU-1C-1985-05 Cud

Description

The transition from solid copper to copper-plated zinc planchets in 1982 fundamentally altered die wear patterns, and CU-1C-1985-05 on the 1985 Philadelphia Lincoln Memorial cent reflects these changed dynamics. Copper-plated zinc planchets — composed of a 97.5% zinc core with a thin 2.5% copper plating — behave differently under striking pressure than the solid 95% copper alloy they replaced. Zinc is softer than copper and deforms more readily, but the composite structure creates a unique stress profile: the hard copper shell resists initial deformation while the softer zinc core yields beneath it, producing a two-phase impact response that loads die surfaces differently than homogeneous planchets. This altered stress transmission can concentrate force at the die rim, precisely where cuds originate. By 1985, the Mint had three full years of experience with zinc planchets, yet die failure patterns were still being understood. The Cuds on Coins catalog documents 31 numbered entries (with CU-14 delisted) for the 1985 Philadelphia date alone, a volume that partially reflects the enormous mintage but also suggests the zinc planchet composition contributed to elevated die breakage rates. Struck at Philadelphia on planchets weighing 2.5 grams and measuring 19mm from the 1985 production of approximately 5.65 billion cents.

Attribution History

• Discovered by Joe Koelling
• CU-1C-1985-05; number: none
• Expert attribution by Cuds on Coins

External References