Here is an 1846 Large cent I picked up today. As you can see there is a lot of pitting in parts of the field and some of the devices. Here is my question, in older coins like this how or what is the easiest way to differentiate between what could be environmental damage and what could just be part of the planchet as a flaw. The coin is a nice XF-40/45 otherwise IMO.
That's corrosion damage. And since there is no sign of the corroding material, at least in the pics, the coin has to have been cleaned to remove it. That doesn't mean it's been harshly cleaned, but it may have been. Planchet flaws tend to be rough, jagged and unevenly shaped and interspersed over the coin. Whereas corrosion damage tends to be always in patches and the marks have a rounded shaped almost like little bubbles or pockmarks.
I agree, but for a different reason (which may be wrong). By this time in coin production at the Mint planchet porosity was a thing of the past. So I'd nix that as a possibility. Am I correct?
For the most part, yes, planchet quality had greatly improved. There were still isolated instances, but very few. We still have the occasional planchet flaw in coins even today.
Agreed about the planchet flaws today, but is porosity still one of the problems? I'd be interested in seeing that.
Looks like environmental damage to me. Porous planchets tend to have much smaller micro-bubbles. I also agree with Kanga... there were fewer bad planchets by the 1840s, and the bad ones tended to be clips or other rim issues. Doug also makes a good point... even today, no mint is perfect.
