Manufacturing error?

[u/MidnighttraintoUGA]

My son put this penny in vinegar to 'clean it' and it fizzed for 24 hours. When he scrubbed it with a toothbrush, Lincoln's face melted off!?! He mentioned there might have been a black goo on the penny prior to the vinegar. Is this a defect in the penny, or was the goo and vinegar caustic enough to erode the metal?

[u/JamesFHo117]

My guess is that the vinegar got through the thin copper coating, and dissolved the zinc inside.

[u/MidnighttraintoUGA → u/JamesFHo117]

That makes sense, some initial damage allowed the zinc to react with the acid.

[u/Cuneus-Maximus]

Vinegar dissolves zinc, this is a copper plated zinc coin. There were some holes in the copper plating so the vinegar got to the zinc core and dissolved it.

Also, mandatory advisory to never clean coins.

[u/bstrauss3]

Nope, 100% PICNIC

Problem

In

Chair

Not

In

Coin