The following is a presentation given by a member of the Numismatic Society of South Australia at the meeting held on Thursday January 19, 2016.
A member showed a 1988 $2 coin which was found by his daughter while noodling rolls of coins obtained from a bank. The obverse of the coin has an impressive planchet flaw across much of the surface. Some other commonly used names for this type of error are lamination flaw or planchet peel.
Planchet flaws happen when coin metal is being rolled prior to blank manufacture. A gas inclusion, metal impurity, or some metal of low temperature is rolled into the metal leaving an area of inherent weakness where some of the coin metal is only weakly attached to the rest. As the metal is rolled the flaw lengthens and becomes linear in nature as does the associated piece of attached metal.
This coin shown at the meeting was struck while all the coin metal was present, but at some point after that the planchet flaw has detached from the main part of the coin leaving an essentially linear flaw across the surface of the coin. The flaw on this coin is much larger than you’d typically see and is a good example of the type.