Nic-A-Date: What Does It Do?

I don't think you are, I think it's the combination - work hardening changes crystal structure (that's why annealing and softening work using the same tool: heat). I think there is also a preference when forming crystals to avoid 'foreign' atoms. But both Nickel and Copper are transition metals and so the bonding structure isn't as simple as non-metals. But that's all from memory of chemistry class long, long ago. I couldn't find anything that actually talks to how it works, just a couple of videos showing the process.

A dateless Buffalo nickel is worth about 15-25 cents. A nic-a-dated common buffalo is worth 5-10 cents. A nic-a-dated key date is worth maybe 25-50% of what a partial date would bring (it leaves an ugly stain) but remember that it was a 15 cent coin previously. You're basically gambling 5 cents on whether it is a better date.

I would only do it on coins with a mintmark, and NEVER do it on a Type 1 raised mound.

Nickels and Cu-Ni clad coins (outer layers) are both 25% nickel to 75% copper.

Acetone is ideal for removing PVC, been using it for 30 years without incident.

Here is one I tried.
The chemical was common vinegar.
The coin, a Liberty head nickel.

before:


after:


Theoretically, I didn't destroy much value.
It's still worth 5 cents.

So another question... It's not something I have to deal with now, but I love colorful, toned coins. Sooner or later I'm bound to get one that has a little PVC. Does acetone remove toning?

Now that I recall, there was some peroxide in the vinegar. I should write this down.

Excellent explanation, Sap.