Would coin struck through water look like one struck through oil/grease?

I'm not really an error collector, but do own an ancient brockage. I see struck-through oil/grease coins offered for sale. I'm curious whether a coin struck through water (sweat, coffee, cola, spit, honey, etc.) would look the same. Surely, the occasional "wet" planchet must get struck.

Cal

 

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In general, liquids are not compressible. Any liquid coming between the dies would tend to dampen out the strike. Oil is more viscous (thick) and would not tend to run off as much as water, but water could cause a "struck through" look.

 

I/we would like to see it!

 

My first reaction was "no".
BUT with the speed of the presses I think it's a distinct possibility.
Water wouldn't have enough time to be completely squeezed out.
Sort of like the hydraulic effect caused when a car tire hits a pothole with water in it.
An almost instantaneous very high pressure "hit" on the road surface.

 

Just wondering if, it would be in a tear drop shape?

 

I think that water would dissipate due to the heat of the die.

 

Gosh. Is this a near-like? Thanks. Cal

 

Ask and ye shall receive. Apology for graininess of pics, but they're old. First pic is the obverse. Second pic is the reverse, which is actually a mirror image of the obverse of a previously struck coin that stuck to the die. Third pic is what a normal reverse would look like.

It's a Roman Republican silver denarius, minted about 55 BCE, by moneyer C. Claudius Pulcher (RSC-Claudia-1). Obverse depicts helmeted head of Roma. Normal reverse depicts Victory in a biga (two-horse chariot) with the moneyer's name below. Coin celebrates the victory of moneyer's ancestor over the Istrians and Ligurians in 177 BCE.

Cal

 

Then struck through beer is out of the question!

 

Not on the job.

 

OP, grease is a solid, not a liquid. That's why, when it gets into the die the resulting impression on the devices is obscured/flattened. As a liquid, water would have some level of lubricity, which would mean, it would spread across the surface when compressed. Additionally, water is a low viscosity liquid, so it would be highly unlikely that it would be able to withstand the 60 tons of pressure and result in any discernible impact on the resulting coin.

Doug, I have to disagree with the basis for the theory, as it depends on the metal composition of the coin in question (Cu, Au, Ag versus Ni) and the coin press and ejection mechanism (Al, Mg versus various steels). I have a feeling that Cu coins would cool much faster than Ni coins, and when the coins are popped into the bin, they're coming into contact with high thermal conductivity products. It's possible that the 60 tons of pressure, over the surface area of the planchet, could, indeed, exceed the boiling point.

I think the bigger concern is that the water wouldn't be exposed to the boiling temperature long enough for it to matter. (Basically, the water would flow away before it could boil off.)

 

Seems speed of the coining press would be a factor. Water can be pretty resistant to flowing if hit suddenly. Try diving into water from 6 feet above, then try 60 feet (2 meters versus 20 in logical units). You're likely to be a little more deformed on impact after diving from the greater height.

Cal

 

GDJMSP said-Very doubtful, and I'm almost tempted to say impossible. What you're suggesting would require a temperature above the boiling point. And the heat generated by striking a coin never comes anywhere near that, not even close. A struck coin could be ejected right into your hand and it might feel slightly warm but there wouldn't even be any discomfort.

And the dies, they might get slightly warmer than the coins, but no where near temperatures like what you're suggesting. Simply put heat is not even a factor, not in any way, when it comes to striking coins.[/QUOTE]


So, Here in Denver, even on a 75- 80 degree day. The rain will dissipate on contact with the ground,

It would really depend on how much water was trapped on the Blank, with out an escape route.

It would be an interesting Math equation if anyone out there, had a die to aid the displacement ratio,

 

Yes, you do not need water to reach the boiling point in order to evaporate.

 

Doing a believable theoretical calculation is probably not possible. The properties of liquids and metals when impacted rapidly with huge force, as occurs with high speed coining presses, likely need to be determined empirically (i.e. by experimenting). Speed as well as pressure would be a factor. With an old, hand-operated screw press, even thick grease might spew-out without leaving marks on the metal. But modern presses apply tons of force hundreds of times per minute, and die velocity at impact must be very high.

I know pure water evaporates quickly outside on warm days in Denver (I was raised there). But how about some spilled cola inside the Philly mint? Wet or sticky planchets likely go through presses once in a while.

Cal

 

That has to do with surface tension and the fact that the surface area of the water exceeds the surface area of the person diving. Also, 60 ft isn't equal to 20 meters... more like 18.3 meters.

Anyway, the situation of a die, press and planchet wouldn't respond the same as a deep body of water. The static fluid pressure of the water in the bottom die would be somewhat negligible, since the thickness of the water would be minimal. As such, the displacement of the water would occur much more readily under force (even at extreme acceleration) of the press.

 

You folks are forgetting that the die faces are not smooth. If you have a drop of water on the planchet and it get trapped by the recesses in the die as the fields press into the planchet, it isn't going anywhere. And it will behave like any other incompressible liquid and prevent the metal from filling the recesses in the die. So it will have the same effect as a drop of grease.

 

I'm quite familiar with metric and nonsensical units and their conversion. I was rounding and don't think it would make any difference to a diver whether the distance to the water was 18, 20, or 19.375 meters.

A bit of water on a planchet has a much stronger backing than the surface of deep water. I don't think lowering or eliminating the surface tension would lessen the blow one bit for someone diving from 60 feet (or 20 meters) into water. If you think it would, give it a try; put detergent in a diving pool. And the pressure at the surface of the water where impact occurs would be zip. You would have to go very deep indeed into the sea to find pressures comparable to those generated by a coining press. Depths no one diving from any height would achieve.

However, I don't think any theoretical arguments will be convincing on whether water on a planchet will leave a mark when hit with dies moving at high relative velocity. Only an empirical test is likely to provide an answer acceptable to me and most folks. Until that time, I'm firmly in the don't know camp, but happy to shoot arrows at theoretical arguments. I spent some of my youth in Missouri; so, show me.

Speaking of which, there's a good chance experiments with strike-throughs using a variety of substances have been done by mint employees. Some authorized, most probably not. Who among us hasn't put a coin on a train track? Does your chewing gum lose its flavor riding on a planchet through a coin press? It must be easy for employees to create a variety of errors; getting error coins out of the mint is another story.

Cal