I just read a description of a Large Cent that included "Lt. porosity" What's that tellin

UncleWiggly

Holes you can see through? Microscopic? The date and grade are 1812 G-VG Lt. porosity.

What about 1851 VF Porous surfaces. Tiny moon craters?

They also use it in a description for one of the "V" Nickels 1884 AG (G w/porosity)

Is this something you can see or tell by appearance? Or do you need to magnify it?

I guess my real question is, does this mean fluids can actually seep/go through the coin kind of like a sandstone fuel filter? It would seem to me if a coin is going to develope porosity it would eventually disintegrate into powder. So, that leads to another question. Is porosity caused by wear or some sort of chemical breakdown?


Thanks,



Jerry

OnlyBuffalos

Porosity is erosion of the surface of the coin caused by heat, cold or humidity, usually by improper storage. It is a very common problem of early copper coinage. The earlier the coin, the more likely some corrosion is present. The porosity can range from microscopic to much worse. It would be highly unusual to find a coin with a hole through the coin that was caused by porosity. Coins which are damaged by chemicals are referred to as chemically damaged and are typically treated separately from coins with porosity. Porosity frequently can damage the color of the coin and it is not uncommon to see "recoloring" of such coins. Many early large cents have been recolored, some so well that even experts can be fooled on occasion.

Some of the most heated arguments result over assessing a grade to a corroded early copper coin. Eye appeal is usually a very major factor in determining a "value" for such coins.

Large cents dated 1814 or earlier are particularly prone to porosity due to the composition of the coin.

Barry

Porosity is actually a bad term as no fluids will seep through like a sponge.

Here's an example (not my coin):

earlwbollinger

It would seem to me if a coin is going to develope porosity it would eventually disintegrate into powder.
Some ancient coins do develop something like a crystaline structure (crystalize), if you accidentally drop them on the table, they really do shatter
and disintigrate into lots of little tiny bits and pieces. The ancient coin may even look quite nice with no outward signs of this having happened to it.

dorkkarl

porosity is overall corrosion. you'll recognize it when you see it. if you don't see it, that means your buying the coin sight-unseen, which is always a foolish mistake.

K S