For a period of over 2,000 years, since the Han Dynasty (206 BC – 220 AD) until the early 20th Century, the standard form of coinage in China was the copper-based quan (or ‘cash’). This was a round copper alloy coin with a distinctive square hole in the centre, featuring an inscription, and cast from a sand-based mould. Such coins were used almost exclusively as the official currency for everyday use in China over this period.
While the exact metallurgic composition of these coins changed over the two millennia that they were in use, the production process remained largely unchanged. Coins were cast, rather than struck – which was the common practice for western coin production at the time. They were cast in two-piece moulds. Moulds were made by softly pressing a master coin into a wooden box filled with sand. The sand was bound with some sort of organic matter so that it would hold the shape pressed into it. A second box was then laid on top and pressed together. The boxes were then pulled apart and the master coin removed. A two-piece mould was thus made, one box containing an imprint of the obverse face, the other the reverse face.
Channels were then made in the sand between the impressions along with a channel in the centre of the mould to allow for the molten metal to run in. The boxes were then fired to harden the sand and organic matter mixture. Now the moulds were ready for use and the metal was poured in, resulting in a t-shaped coin tree. The coins were then separated from the tree and then filed to smarten them up, removing any remnants of the tree.