Hairline. The narrowest and earliest form of diebreak; as the width of a hair. Hairline diecracks tend to "grow" – to lengthen, widen and deepen on successively struck pieces as the break progresses in the die. See broken die. The finest engraved line of a hand engraver is also called hairline; an example would be the minimum width line in script lettering. A fine pointed graver is used to make such a cut with a minimum depth.Collectors sometimes call fine line scratches on the surface of a numismatic item hairline scratches.
excerpted with permission from
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor