internal cuds and retained internal cuds
- While we're on the subject of cuds, I thought I'd mention the
existence of an error type that has escaped notice. This is
the "retained internal cud".
When a large flake spalls off the die face, and is unconnected to the
rim, it is called an "internal cud" or a "large interior die break".
Large internal cuds are most often associated with split dies.
I have seen a number of split dies in which the split seems to
bifurcate and pass to the sides of a weakly struck part of the design
that is raised above the level of the rest of the design. This
apparently reflects the presence of a retained internal cud. It
seems that a rather thick flake (perhaps roughly triangular in cross
section) sinks into the die face, quite possibly acting as a wedge to
drive the two halves of the die face further apart.