I Paid My Tuition, Please Someone Help Me To Learn My Lesson

Sorry- I just now read this post, every time I try to leave for a few days I miss something!

We will take worn coin so long as it is identifiable as to what it once was. The worn coins go into the bags of coin we send in for credit. The bags are weighed, not counted, so it doesn't matter what kind of scudzy stuff is in there. However, we won't take coin that is encrusted with crud or sticky stuff because it will mess up our machine, and that thing has enough trouble already!

Worn currency is a different matter. We will take it, as long as it meets certain guidelines. One whole serial number and at least two-thirds of the second must be there. We just take it down to the bigger bank down the street and turn it in for newer bills. We could send it back to the same place we send our coin, but it has to be part of a full strap. That means we'd either have to keep it around until we got a full strap of worn out currency ($2000 in 20s, $1000 in 100s or 50s, $500 in 10s, $100 in 1s and 5s), which would take forever, or we'd send it back as a part of a "good" strap, and we don't ever have any money left over each week to send anything back!

Hope this helps!

Rachel [:p]

quote:

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Originally posted by crystalk64

They look like the real thing to me as I don't see a counterfeiter wasting his time on common date Morgans or Peace dollars.

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There was a fair amount of time (late 1870's-1960's) when silver was less valuable than the dollar coin was so it paid for counterfeiters to make fakes out of the proper composition, and a quality fake could double (or better) the faker's money when spent at face value.

Bob, what is spark erosion? I've had a little (very little) metallurgy, have done sand and mould casting (currently .50 calbre bullets from 40/60 solder bars), am somewhat familiar with casting techniques (I can drop an occasional term like "lost wax process"), but without doing a major Google am not familiar with spark erosion.

Are you by some chance in a profession related to metallurgy? Your knowledge is phenomenal!

Fred

Morgan Fred - Spark Erosion is as the title implies a process based on getting an electric spark to pass from one electrode (the host coin - the one being copied) onto a second electrode (the metal plate that will be the die or mold face). It is done in an electrolytic solution. The gap between the host coin and the metal plate is very small and the discharge passes from the closest point of "near" contact - eroding both the plate and the host (to a lesser extent). The result is an exact copy of the host with some pitting of surfaces and loss of fine detail. The fields are usually polished to eliminate the pitting but the pits can not be removed from recessed areas of the die/mold.

Classic spark erosion copies were etched into steel plates and the steel dies thus produced were used to strike counterfeits. Several sources point to only small diameter coins being copied by spark erosion techniques, but I am aware of larger coins that have been copied in a similar fashion.

But in this specific case, I believe that the counterfeiters used the same process to produce molds in a softer metal. I don't believe the coins were struck because of the total lack of any flow lines and the obvious casting features visible on the finished product (e.g. the fold near the rim under the date on the 1886). The edge application of the reeds is also more consistant with a post (strike/cast) edging followed by grinding down (chamfering) the sharp corners.

I settled on spark erosion as the methodology used because I am not aware of another transfer method that would produce the surfaces I see here on the details especially the depression mimicing the crown of Liberty's head on the 1922 coin.

I am a retired Structural Engineer and I did take courses in metals and materials in college - but most of my knowledge of metalurgy with regards to counterfeiting is self taught. There are numerous very good publications on metals and metal working - some of which relate specifically to coinage while others cover general metal manufacturing techniques. Of particular interest given my area of concern are the publications dealing with the history of metalworking. For instance if you know that German Silver was introduced about 1835 in the US - and you have a German Silver forgery of a 1770s coin - you know it was not made contemporaneously. Likewise, the fact that simple electroplating is a technology never used prior to about 1840 limits which coins can be believable as contemporary issues.

Larson's recent book on forgery is a good starting point for learning the various techniques forgers employ to transfer an image.

Hancock and Spanbaur did a book back in the 1970s I believe which is interesting because of the stories he tells. But as far as techniques used in Forgery - Larson is best.

I like Larson's book. It's different than a guide book in that he writes it from the point of view of the forger. So the things that the forger is trying cover up or avoid all together, like vacuuming plaster to get air bubbles out, become the things that the coin collector will look for.

The only thing about the book is if you don't really understand how coins are made--hubs and dies, your going to be lost. There's were a few times where I had to draw out the process to understand what he was talking about. He tells how forgers can make a mintmark punch with a nail that I just couldn't get until I drew it out--mintmark cut into piece of metal must be incuse negative, becomes raised positive on nail, becomes incuse negative in die, becomes raised positive on coin... I'm not complaining here about that. It's probably necessary to understand dies in order to understand how coins can be forged.

It's a good book and it will scare you when you see just how cleaver these people can be.

Well, I definitely got my money's worth from this particular tuition payment. Thank you so much, Bob et al.

I'm glad to see the class had many auditors who also benefited.