Lincoln Cents And Zinc Rot?

Highly unlikely Hams. 1982 is the year with all the different versions. You can always weigh a questionable zinc core cent.
3.1 grams would be non-zinc, 2.5 grams would be zinc core. Hope that helps.

No the zinc planchets were introduced in mid year 1982.

Lincoln Cents are zinc planchets plated in copper since 1982 and this process took a while to perfect. The plating didn't often completely adhere to the zinc planchet and so the air in these areas would expand and create bubbles of all shapes and sizes which look like freckles, or jokingly measles or a leper you are seeing. You can actually poke and burst these shapes and bubbles.

Once these pockets are breached it doesn't take long for the zinc bloom or Hydrozincite to form and eventually zinc rot to occur. I can imagine its far worse going through pocket change as those coins of course the copper may have be worn exposing the zinc, or were exposed to elements. I can see why some would want to avoid them unless they were still uncirculated. Plating bubbles don't add any value to a coin, but collectors have paid a premium for them mistakenly because the coin was misrepresented as something else or the collector thought it was something it is not. An extreme example of plating bubbling however might go for a few dollars on occasion, or such that it impacts the design in some way.

Zinc rot is like the equivalent of a zombie, dead but not as its still spendable. In 1982 when the rising cost of copper made the cent more expensive to produce than its face value, a new composition of copper-plated zinc was adopted for the cent. These cents had a core composed of 99.2% zinc and 0.8% copper, with a plating of pure copper. It is a very unstable combination. Often around the mintmark, small breaks of the plating occur as the coin is struck. That spot is a prime target area for corrosion to begin under the copper plating. Other reasons such as damage can also allow the inner zinc core to be exposed and once that does the whitish substance will form as a protective barrier but when worn off from further circulation makes the rot continue. Unfortunately these don't have a premium, are common, and usually will get worse over time if the zinc continues to be exposed to the atmosphere. This happens because people put them back into circulation. The good news is that if you don't disturb the whitish protective barrier, they should not deteriorate further unless it was a major break in the copper at least. As far as the black spots on the shield cents,I havent been paying as much attention.