Early copper question

longtimecollector

What's considered "worse" by early copper guys..... corrosion or porosity ???

Prethen

Corrosion.

Longacre

I am not an EAC person, but that is an interesting question. What causes porosity? Is it corosion that has been stopped? Or is it a defective planchet?

coinguy1

Some people use the two words interchangeably, but I think that is incorrect.

Many early copper coins were struck on porous planchets (the very rare 1793 Liberty Cap Cent type quickly comes to mind). Corrosion, on the other hand, generally refers to a process which occurs AFTER a coin has been struck and is less acceptable than porosity.

BillJones

They are both things that I avoid, which is why I don't collect very much early copper any more.

Actually they can go hand and hand. A corroaded piece can have the corrosion cleaned off of it, and then it's porous. Either way it's not the type of copper that I want, but given the fact that a cartel controls the copper market, that's about all there is to buy these days.

Collecting early American copper isn't much fun any more, and yes, I'm a long standing member of the Early American Coppers Club.

longtimecollector

Can anyone describe the difference between porosity and corrosion???? I have an early cent that was net graded as corrosion....... It would best be described as a microscopic roughness which is even across the entire obv & rev........ almost like a micro-etching....... How do I know this wasn't a defective planchet ?

coinguy1

Edited: post deleted in order to avoid possible confusion.

BillJones

Chances are it's not a defective planchet. There are a few issues, like the 1793 Cap Cent and the 1811 half cents, which were struck on porous, junky planchets, but by in large most all of the defects got there after the coin left the mint. In the case of the 1811 half cents, the mint director of the time hated the denomination and had all of the planchet stock available, which included a lot of bottom of the barrel stuff struck and issued. 1802 half cents come on crummy planchet stock too because the issue was made from spoiled large cent planchets that were heated and cut down to size.

Corrosion is the most often green but also black or red raised stuff that appears on the surface of the coin. Porosity is the pitted stuff you see on the surfaces. It can range from fine to as deep as a crater. Usually it is the result of corrosive activity or the result of corrosion that has been removed from the piece.

rays

And how about "verdigris"?

MadMarty

Here you go, my early coppers...

BillJones

<< <i>And how about "verdigris"? >>



"Verdigris" is usally some copper oxides that MIGHT lift off if one carefully does with a little brushing with a goat hair bush. Once it is set verdigris might be viewed as a very light form of corrosion. Usually the affects of verdigris are not as bad as the effects of outright corrosion on a copper coin.