@dcarr said:
The "discoloration" is a striking issue. The spots are opposite the scroll ends on the reverse, which is the highest relief that is close to the rim. The planchet surfaces in that area are not work-hardened the same as other areas. This can cause some differential toning (spots) because the amount of work-hardening affects subsequent toning.
Thanks @dcarr! This helps in understanding what is going on with these cents. I am assuming work hardening is the pressure applied by the dies?
@dcarr said:
The "discoloration" is a striking issue. The spots are opposite the scroll ends on the reverse, which is the highest relief that is close to the rim. The planchet surfaces in that area are not work-hardened the same as other areas. This can cause some differential toning (spots) because the amount of work-hardening affects subsequent toning.
Thanks @dcarr! This helps in understanding what is going on with these cents. I am assuming work hardening is the pressure applied by the dies?
"Work hardening" occurs in most metals when they are stressed. For example, take a malleable length of solid copper wire and bend it back and fourth. Eventually, the metal in the bend area becomes less malleable, harder, and more brittle - to the point where it breaks. Striking a planchet is also a form of work-hardening, where the depth of relief affects the work-hardening to a different degree in different areas.
@dcarr said:
The "discoloration" is a striking issue. The spots are opposite the scroll ends on the reverse, which is the highest relief that is close to the rim. The planchet surfaces in that area are not work-hardened the same as other areas. This can cause some differential toning (spots) because the amount of work-hardening affects subsequent toning.
Thanks @dcarr! This helps in understanding what is going on with these cents. I am assuming work hardening is the pressure applied by the dies?
"Work hardening" occurs in most metals when they are stressed. For example, take a malleable length of solid copper wire and bend it back and fourth. Eventually, the metal in the bend area becomes less malleable, harder, and more brittle - to the point where it breaks. Striking a planchet is also a form of work-hardening, where the depth of relief affects the work-hardening to a different degree in different areas.
It appears there many of these W cents with the work hardening issue. Thanks again for the info @dcarr.
Comments
Thanks @dcarr! This helps in understanding what is going on with these cents. I am assuming work hardening is the pressure applied by the dies?
"Work hardening" occurs in most metals when they are stressed. For example, take a malleable length of solid copper wire and bend it back and fourth. Eventually, the metal in the bend area becomes less malleable, harder, and more brittle - to the point where it breaks. Striking a planchet is also a form of work-hardening, where the depth of relief affects the work-hardening to a different degree in different areas.
It appears there many of these W cents with the work hardening issue. Thanks again for the info @dcarr.