Part IV. Die Errors:

Die Clash:

Collar Clash

A collar clash represents damage to the rim gutter of the die from contact with the collar.  It shows up most clearly in reeded issues, where it takes the form of serrations along the top or the edge of the design rim.  In an off-center strike, a collar clash will appear in the form of parallel grooves in the “slide zone”.

Collar clash is far more common on the hammer die.  It occurs when a temporarily misaligned hammer die collides with the top of the collar and/or scrapes along its working face.

When collar clash occurs on the anvil die, it is probably from a repeated up-and-down scraping action of the die neck against the working face of the collar.  However, a sharp sideways impact that drives the die neck into the collar’s
working face could also produce this pattern of serrations.

Below is a 1997-P dime with a collar clash from from K8-K12.

Another collar clash on a 1980-P Kennedy half dollar seen from K7-K11.

Below is two views of a defaced state quarter working hub with evidence of a previous collar clash. The grooves match the width and spacing of the reeding found on a quarter. The face was ground off down to the level of the rim gutter leaving some of the collar clash marks visible.