Lamination errors are a type of coin error that occurs when foreign bodies or impurities, such as metal dust, slag, debris, and so on, are trapped inside the melted metal used to produce new planchets. These foreign bodies become a part of the planchets and subsequently the coins produced from them. If foreign bodies were present during the production of the planchets, they tend to peel off, resulting in metal losses before or after minting due to the presence of contaminants in the alloy. This phenomenon can also occur when planchets are composed of multiple layers.
Lamination Errors
In extreme cases, the planchet can split into two distinct sections, forming two circular planchets of lesser thickness, known as “split planchets.” A split planchet before striking will have streaks on the face involved in the separation, with the texture varying from coarse to fine. A coin struck on a split planchet before strike will always weigh less than a normal coin, and most of these split coin planchets before strike exhibit weak beating, as the planchet is thinner.
In the case of a split coin planchet after strike, the side involved in the separation will have streaks on the face, and it will present a spectrum in incuse and regular position of the embossed reliefs on the opposite side of the coin (the one not involved in the separation). This error is sometimes mistakenly referred to as “uniface,” but it cann’t be designated in this way because the planchet is minted correctly on both sides, and the separation takes place after the minting process.
On the above image, you can admire a magnificent complete split coin planchet after strike (pair from the same coin) from the same collection, separated into two distinct sections after minting. It is possible to find a complete split coin planchet, although it is exceedingly rare.