BronzeWork

An Historical Perspective

The earliest bronze was probably made by accident. Some copper ore deposits also naturally contain small amounts of tin. When such ore is refined, the metal looks like copper but is harder and more useful for making tools, weapons, and artwork. Sometime around 3,000 BC, metal-workers in Mesopotamia found that if they added a small amount of tin ore to the copper ore during smelting the resulting metal was harder and thus more useful than either tin or copper alone. They had created the alloy bronze. Furthermore, the addition of the tinstone reduced the temperature required to melt the metal and, once melted, the bronze was more fluid and easier to cast. The first examples of bronze used in any quantity have been found in the tombs of Sumerian kings who ruled in the lower Mesopotamian Valley. With increased trade in the eastern Mediterranean, this bronze technology made its way into Egypt, and the Egyptians were using it in a limited way by around 1,500 BC. However, bronze was not in common use in Egypt until about 1,000 BC

Bronze was also stronger than iron, another common metal of the era, and quality steels were not available until thousands of years later. Nevertheless the Bronze Age gave way to the Iron Age as the shipping of tin around the Mediterranean Ocean ended during the major population migrations around 1200 - 1100 BC, which dramatically limited supplies and raised prices.

The Greeks developed bronze casting enormously. For sculpture, bronze offered freedom from the limitations of marble which they explored to the full. A famous example was an enormous bronze statue of Apollo. Cast in sections, when assembled it towered 105 feet above the harbour entrance to Rhodes, with one foot on each pier head. The statue weighed some 360 tons and was one of the seven ancient wonders of the world. The Greek foundrymen had also established some useful alloys, recognisable today. As Pliny mentions in his Natural History "The composition of bronze for statues, as well as for sheets of metal, is as follows: the ore is melted and to the melt is added a third part of copper scrap-that is, used, second-hand copper. This scrap contains an intrinsic, seasoned brightness, since it has been subdued by friction and tamed by use. Tin is also alloyed with it, in the proportion of one part of tin to eight of copper.

"Then there is the bronze referred to as 'suitable for moulds'; this is very delicate because a tenth part of lead and a twentieth part of silver-lead is added; it is the best way to impart the colour called Grecian...." (Natural History 34.97-98).

Until cheap steel became available in the mid 19th century, the limitations of the maximum temperature of wood or coal fired furnaces meant that bronze continued to be cast and iron was wrought. The painstaking beating and folding of iron sheets created an early version of steel, used mostly for critical applications such as sword blades and tools. The legend of the sword in the stone is reputedly based on the process of forging a steel blade. The person who possessed the technology to create a better sword was in those days more likely to be king.