"Rust" on Morgan dollar dies.

RWB

The quote below comes from VAMworld's current “VAM of the Week” 1897-P VAM-6A. Does anyone know where the following concept originated?

Pitting on the reverse of Morgan Dollars isn't uncommon - the reverse die was the "anvil," the bottom die and as such able to capture pooled water and then rust …

Wolf359

The Big VAM book calls the die "pitted" but does not call it due to rust.

I don't know. There aren't any reported from Carson City. Since it's mostly New Orleans and a few Philadelphia dies and a very few San Francisco dies this happens to, I assume it's something in the weather. More humidity - more chance of rust = more pitted dies.

Buffalode

I don't know the answer but is it possible pitting could occur without the rust? If water did collect on the reverse die, could that water be vaporized during the striking process from heat and pressure? Cavitation air bubbles can cause pitting of ship's propellers. I wonder if something like this could occur over time on the surface of a die from either steam, or a "water hammer" effect from trying to compress a liquid?

FredWeinberg

Aside from the fact that we know the Reverse Dies were the anvil dies,
because every single Partial Collar Morgan dollar I've ever seen has the
partial reeding on the reverse side, I've NEVER heard of this 'water pooling'
concept.

There's grease around the machinery, but unless the presses are being
used in the Philadelphia area rivers, I'm not sure what that concept
means....never heard of 'captured pool water' in the presses, or on the
reverse dies, etc.

messydesk

I haven't heard of that, either. Not sure how the water would pool on the high points of the die and then not be vaporized after one or two coins were struck.

AUandAG

In my library somewhere is the explanation that the dies were stored on shelves with grease
covering them to protect them from the acidic atmospheres found in the mints. Occasionally
one die would be stored with no grease, or partially greased, and the acid attacked the surface
of the dies and then the resulting use of the dies it produced a coin with a "rusty" appearance.

Don't know how true this is but it sounded okay to me.

We do know that the smelting processes in the mints were in fact very caustic. Wood was used
in the furnaces and that would add more moisture to the buildings. Steam was bleeding off as
the presses were steam operated and that contributed to the process of die damage. When you
have exposed steel, moisture and acid you will get damage.

Thought that that made a lot of sense. Perhaps it's not correct and just whimsy.

bob

RWB

The part about water pooling on the reverse die seemed strange, and odd to see that claim on VAMworld's featured coin. Anyone know where the VAMworld poster got his info.?