1. What was the exact process of striking hammered coins? Any noteworthy variations to the basic process?
2. What are the various methods of casting coins? What physical characteristics of a cast coin can allow one to tell the type of casting method used in it's manugacture?
3. What physical characteristics, if any, allow us to distinguish a struck coin from a cast one?
I would greatly appreciate detailed answers, with images if possible. Links to sites giving information on the above/reference books would also be very useful.
Quote from: Overlord on February 07, 2009, 04:44:15 AM
1. What was the exact process of striking hammered coins? Any noteworthy variations to the basic process?
a) Mount a lower die in a big block, usually wood. This die often has a spike for mounting underneath
b) Fix the upper die on a sturdy metal handle.
c) Hire a big brute with a hammer
d) WHAMM
variations: in Roman times, sometimes two brutes were working on the same pair of dies to increase speed, taking turns at giving a blow, while a third worker would put the planchets in place. The Romans also developed a sort of metal pincers for hammering coins. Presumably, these were for very small coins. In the middle ages. very thin coins were struck with the reverse being the obverse in incuse (bracteates). Some theorists believe that wooden dies were used for these coins. Others say that several coins were hammered at the same time.
Quote from: Overlord on February 07, 2009, 04:44:15 AM
2. What are the various methods of casting coins? What physical characteristics of a cast coin can allow one to tell the type of casting method used in it's manufacture?
I know of only one method. The following is based on Chinese production methods.
a) produce "mother" coin in hardened metal
b) press "mother" several times in malleable material, such as clay in two boxes. Make sure obverse fits reverse.
c) draw main channel and side channels from each impression to main channel
d) fix mould halves together
e) pour in molten metal, making sure that air can escape (tricky!)
f) let metal cool
g) break mould, break coins from money tree
h) file away parts of channel sticking to coin (square holes help to mount coins on stick, so that several can be files at once)
Variation: forgers would sometimes cast their imitations in sand, each side separately, fix the two halves together and file the edge. AFAIK this method was never used for official coins.
Quote from: Overlord on February 07, 2009, 04:44:15 AM
3. What physical characteristics, if any, allow us to distinguish a struck coin from a cast one?
The famous "ping" test (http://www.worldofcoins.eu/forum/index.php/topic,149.msg366.html#msg366).
Quote from: Overlord on February 07, 2009, 04:44:15 AM
I would greatly appreciate detailed answers, with images if possible. Links to sites giving information on the above/reference books would also be very useful.
Thomas W. Becker:
The Coin makers (http://www.amazon.com/gp/offer-listing/B0006BV1XI/ref=sr_1_olp_1?ie=UTF8&s=books&qid=1234043397&sr=1-1)
Peter
Thanks a ton, Peter. I also found information on different casting methods (with photographs of examples) here (http://www.calgarycoin.com/reference/fakes/cast.htm).
@ Hammered coins
What did a planchet look like?
I read yesterday that the Hepthalo-Sassanid coins (Sassanian types struck by the huns) employed an interesting technique. Apparently, they would stamp the reverse die first, place the coin on the anvil, take out the obverse die, and WHAM. Consequently, the motif on the reverse was crushed.
Overlord,
I tried to attach a picture showing a coin workshop around 1500 A.D.
As you could have seen (bottom left) the plachets are cut out with a huge pair of scissors. The results would be planchets being only roughly round.
But the upload directory of this forum is full. I will upload the picture asap.
Regards,
a3v1
Second attempt!
Regards,
a3v1
Thanks a3v1.
Detail: the guy in the centre foreground is making the planchets, by hammering them out of a sheet. It is his responsibility that the planchets are of the right weight. The fellow with the scissors-like instrument is checking the diameter. Note the hook at the end of the left handle. It has a scale for several diameters. The part where the coin is measured has a mark where the coin should fit. Before him is a pot with the products of the sheet hammerer, to his right a saucer with the approved planchets. These will go to the brute who's actually striking the coin.
The scene is unrealistic in that everyone was checked by someone else, several people were doing the same thing and the mint master would certainly not sit anywhere near the oven, which would be a hot and uncomfortable place. This is because the picture was made to educate emperor Maximillian I on coin production. The points of importance to him would have been the mint master, who is seen "selling" coins to a merchant and the "pyx" in the centre foreground, containing a random sample of the production.
Peter
Quote from: Figleaf on February 12, 2009, 09:41:18 PM
These will go to the brute who's actually striking the coin.
Peter
Thanks Peter. I had thought that the hammer used for striking the coins would be huge. The one in the engraving doesn't look too big.
Quite right. The hammer in the picture seems too small to me. I hammered a few coins. My experience is that you can use a regular hammer. So why do you need a big brute? First because striking goes on for hours on end at a relatively high speed, second because the dies and the planchet are pretty stiff. In other words, when you hammer a nail into wood, the force of the blow is softened considerably because the nail moves into the wood. If you strike a coin, most of the force of the blow reverberates right back into your body. The combination of the two is such a burden on the body that I expect that the minters worked in relatively short shifts.
Peter
Quote from: Overlord on February 07, 2009, 04:44:15 AM
1. What was the exact process of striking hammered coins? Any noteworthy variations to the basic process?
2. What are the various methods of casting coins? What physical characteristics of a cast coin can allow one to tell the type of casting method used in it's manugacture?
3. What physical characteristics, if any, allow us to distinguish a struck coin from a cast one?
I would greatly appreciate detailed answers, with images if possible. Links to sites giving information on the above/reference books would also be very useful.
Cast coins:
http://www.calgarycoin.com/reference/fakes/cast.htm
Many study images on different types of fakes:
http://www.forumancientcoins.com/fakes/index.php?cat=5
Thanks, thelawnet.
Digging up this thread, because I could show in another thread (http://www.worldofcoins.eu/forum/index.php/topic,7597.0.html) that my speculation that Indian coins were hot-struck is supported by experts. Hot-striking is a variation in the process not mentioned above.
Peter