8.1 Purification of the gold
To comply with the requirements of the ZAR Coinage Act (Act no 14 of 1891) Cooney had to purify the gold to 24 carat. The testing was done in the essayer's laboratory for which the Field Mint had to pay £11-6-0 for the use of the laboratory59.
8.2 Melting process
The team activated the mine's coal furnace house and heated the gold in a crucible to a melting point of ±
1064°
Celsius.
8.3 Pouring the gold
The molten gold was cast in a greased slate form that had been preated to prevent it from cracking. The slate form was 5 mm thick, 7.5 cm wide and 15 to 25cm long60. In Perrin's 1874-submission, gold strips with a thickness of 1/3 inch (8mm) and a length of 61/2 inches (16.25cm) is prescribed61. It seems to be a standard size, which underlines the thesis that the minting of Veldpond was not a trial and error exercise but that somebody at Pilgrim's Rest had knowledge of making gold coins. The Mint team must have hollowed out the slate themselves as the mine only cast gold bars and would, therefore, not have slate forms.
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Slate wherein the molten gold was poured.
Coins and pieces of rolled out gold are on top of it 62
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8.4 Rolling the gold
The rolling mill is the most important machine in the whole process of making gold coins, according to Perrin. He prescribed cylinders of no less than 1 ft in diameter (30 cm).63 Mines did have big rolling machines with which steel plates were bent. A logical conclusion is that the minting team used that machine for rolling out the gold.64
The cast gold strip had to be rolled out several times until the correct thickness was reached. After each rolling session, the gold hardened and had to go through a process of annealing that entails heating it in an oven at a low temperature (200°
Celsius) for 45 minutes and then cooling down slowly. When the desired thickness was reached, the gold strip was softened once more so that it could be cut into circular discs and the design imprinted on them. The correct heat treatment of the gold plates was most important as it could lengthen the life of the dies.
Kloppers 65 told journalists that the Lydenburg alluvial gold cracked when it was rolled out and that he got the bright idea to use mercuric sublimate 66 from the mine's first aid stock and added it to the gold, after which it rolled out like butter. The mercuric sublimate would not have any effect on the malleability of the gold, as it would evaporate when heated. The Field Mint did made use of mercuric sublimate for which they paid the mine £167. It was most probably used to recover golddust.
8.5 Turning the dies
The dies had to be made out of small rods of 20mm wide and 15mm thick that would fit in the mine's punching machine.68 The electric metal lathe in the mine's workshop was used but it had to been turned by hand. After Reid turned out each die, heating it to a light straw colour, keeping it at that temperature for 30 minutes and then cooling it down slowly to be annealed .That would give a soft enough product for Kloppers to engrave.
8.6 Letter design
Kloppers designed the coins. His first effort was engraved on one of the mine's copper rulers and then imprinted in lead. This design was rejected. Marshall69 got the ruler with the proof dies and Field Cornet Pienaar70 the lead proof pieces, which they kept as souvenirs.
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Rejected proof dies on a copper ruler of the mine 71 |
Proof coins, in lead |
The second design was accepted. Becklake72 wrote in his book:
It will be acknowledged that the later dies are greatly superior in design and artistic merit to the earlier pair tested, and one is impressed, in considering these pieces, with the skill and ingenuity which was displayed, firstly in the work of refining the gold (Mr. Cooney was the essayer), later in melting and pouring the necessary gold bars, and, finally, in stamping these blank pieces.
8.7 Engraving the dies
Beeswax was put on the surface of the dies and Kloppers drew his design in mirror writing on it. An acid that eroded the design in the steel was dropped on to it.73 Reid and Barter mentioned the use of acid, but Kloppers denied it and said that the design had been drawn on the steel with a pencil. Kloppers engraved the design with a fine chisel and a light hammer. On the one die was engraved EEN POND and on the other ZAR 1902. Kloppers used a small chisel, which also had to be made in the workshop.74
8.8 Hardening the dies
The next step was hardening the dies. Kloppers claimed that he did it and that six dies cracked in the process. This is not true as Reid the blacksmith hardened the dies. None cracked in the process because case hardening had been applied.75 With case hardening the dies were packed in a mixture of ground bone and charcoal inside a container that was then sealed of and heated. The outer steel absorbed the carbon, thereby creating hardness on the outer steel, while still preserving the toughness of the softer iron core. Uniform hardening by heating and quick cooling down would have created a product too brittle for stamping the coins.76 Both Pienaar and Kloppers testified that only one pair of dies had been used. 77
8.9 Cutting blanks
Blank circular discs were cut out of the gold strips with the small hand-punching machine in the photo below. The machine was a small screw press that had been used at the mine to cut holes into steel plates for joining them together with bolts. The sizes of standard punches are 5/8 and 7/8 inches. Converted to metric measure, 7/8 inch equals 2.1875cm and this gives us the size of a Veldpond of which the diameter was 2.28cm. With the pressure on the blanks when the press was turned on, the gold would expand to the milled edge.78 The result was a somewhat smaller gold pound than the standard but, to compensate for that, the Veldpond was a bit thicker than a standard gold pound.
Blank discs could only be punched out of the middle of the gold plates, because the sides would be thinner than the middle.79 The bits and pieces as well as discarded blanks, were melted, poured, rolled, annealed and cut again.
According to Stoker80 every coin was weighed on an essayer scale and those that were too heavy were scraped off and those that were too light were melted again. Mr JT Becklake, later head of the Royal Mint in Pretoria, weighed 17 Veldpond and found that the weight varied between 7.544 grams and 8.508 grams.81 The difference in weight could be ascribe to the fact that gold is a soft metal and that some coins had weared out more than others.
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Small hand-punching machine82 of the TGME mine compared to Perrin's sketch of 1874 |
8.10 Stamping the blank pieces
For imprinting the blank discs with the coin marks, the team used the mine's big electricity driven punching machine. Electricity was not available and the mint team had to apply muscle power. Strong poles were attached to the flywheel, which made it possible to apply sufficient manual force for stamping the coins.
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The big punching machine of TGME compared to Perrin's sketch of 1874 |
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Strong poles attached to the flywheel83 |
The team at Pilgrim's Rest skipped one stage that is usually applied to minting and that was to provide the coins with a raised edge.
The engraved steel dies were attached to the machine: obverse to the top and reverse to the bottom. Reid made a collar for the outer edge. Kloppers filed flutes on it. He judged it by eyesight and at the end there was an opening that was too big for one flute and too small for two. He then made two small flutes close to each other with a thinner file (5 o'clock position seen from the ZAR side).84 The milled collar was attached to the reverse side die.85 With a blank gold disc in-between, the screw was turned on to imprint the markings on both sides of the coin.
The two flutes in the milled edge close to each other are characteristic of a Veldpond. This is however not a test of originality. Veldpond did not always impress uniformly and the flutes were not all filled up. A well-impressed Veldpond would have 76 equal flutes with the two small flutes in the milled edge.
In a letter from Willy Barter addressed to John Hunter McLea86 he mentioned a ringing test. That would have been to test the coins for cracks and flaws.
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