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Lamination Error

Lamination Error.  The unintended separating of layers of metal in a planchet or struck piece; debonding. Also called delamination. Such lamination errors are due to poor annealing, imperfect mixture of alloys or flawed bonding, particularly of clad compositions. Some causes start with the mixing of metals to form the melt of the coinage alloy. Instead of a homogeneous mass of correct alloy formula, an incorrect mixture of metals is formed, called a bullion blunder. When foreign objects or gas pockets (occluded gas) is introduced, this is called alloy imperfection. In the United States, the wartime silver nickels (1943-45) were particularly susceptible to such alloy imperfections and exhibited such lamination exfoliation.

There are three different lamination errors as follows:

?       Peeling, flakes.  If only a portion of the surface separates from the rest of the planchet or coin, this is called peeling where a portion flakes off. This can occur before or after the blank is struck into a coin. Those that flake off before being struck would result in an imperfect coin (these flakes are never found with the finished coin). The flake can separate at any time, however.

In the rare instance when the flake comes off in the coining press, it can fall on its own or another blank to be struck. When the flake comes off of an already struck piece and is impressed into another blank it is called dropped letter. The flake, usually from a high stress area (like the legend), often contains a letter; since it had been struck before it is in work hardened state, it is easily impressed into the soft blank.

?       Split planchet.  If the entire laminated surface on one side of the planchet or coin

separates, this is known as a split planchet. Either or both pieces could be struck separately if the split occurs before being fed into a coining press. Should the piece be struck first then split afterwards, the obverse and reverse would appear normal, but the two interface surfaces would show evidence of the cleaving apart – usually irregular striations.

?       Clamshell.  When a layer of metal separates from the main portion of a coin but does not break off it is called a clamshell by collectors because of its appearance. If the attached portion is not great, they could be separated. The portion still unsplit is called the hinge. They are found in both solid (homogeneous) alloys, but more commonly on clad coinage (as post 1965 U.S. coins).

Observing the main portion of a lamination error where the layer has been removed displays how deep the design is struck into the mass of a coin; while the design at this depth is indistinct it exhibits that the design is more than surface displacement of metal. It penetrates deep within the mass and proves that the design is not formed by surface displacement alone, but metal flow comes from throughout the metal blank.

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators


Roger W. Burdette, Editor

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