Nic-A-Date: What Does It Do?

Nic-o-Date is an acid that brings up the date on a worn dateless Nickel . This doesn't make the coin look pretty ,but if you find a rare date and mint it will have some decent value .
I presently soak my worn out Nickels in a solution of Peroxide and vinegar . this acidity solution also will bring up the dates with decent results .

The process of minting a coin causes a deformation of the metal crystals in the metal, in much the same way compressing a bunch of packing peanuts into a complex shape might break and deform some of the peanuts.
Because the metal crystals of the coin are changed in areas of sharp contour, like the date, the mild acid will act on deformed crystals differently than it will on undeformed crystals.
Wipe wood stain on a polished board and you will see how the stain varies with grain density and direction.
In the best of circumstances, the traction rates will be visible.
My experience is that an equivalent home made brew had only modest results. But it was enough to fill a slot in the Buffalo nickel collection.

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.