Did you ever wonder why Lincoln cents are called pennies even though they are not pennies? How about why Lincoln cents are made with Copper? Why are they round? Why do the have Lincoln's profile on them?
Everyone has questions and this is the place to ask them. Just use the "Contact" link at the top of the page to send us your questions. We will do our best to give you the answers.Why do the modern Zinc cents get "Zinc rot" while the 1943 cents that were coated with Zinc rust instead?
Zinc rot is actually galvanic corrosion between the Copper and Zinc layers.
The Copper plating on cents is very thin and during the striking of the coins, the plating can sometimes split open. Sometimes this splitting is large enough to see, such as we see with split plate doubling. The sharper edges on the die, where the devices are, sometimes catches on the thin Copper layer and it tears. One area that is notorious for this is the mint mark. This crack in the Copper plating can allow moisture to get between the two metals. Now we have two dissimilar metals with an electrolyte (the water) in place to create a tiny galvanic cell. Rapid corrosion of the Zinc will occur creating what we call "Zinc rot".
Something similar happens with the Zinc coated Steel cents from 1943, but once the Zinc starts to break down rust will form on the Steel core. The rust can sometimes seal the damaged area from exposure and stop the process. If the Zinc coating is very thin, or the rust too agressive, the coin will eventually get over taken by the corrosion and rust away.Next Section