The History of Brass - From Coins to Modern Ammunition
From Rajasthan to Waterbury: 2000 years of brass
Copper-zinc alloys were produced as early the 5th millennia BC in China and were widely used in east and central Asia by the 2nd and 3rd century BC. These artifacts, however, may be best referred to as 'natural alloys,' as there is no evidence that their producers consciously alloyed copper and zinc. Instead, it is likely that the alloys were smelted from zinc-rich copper ores, producing crude brass-like metals.
Greek and Roman documents suggest that the intentional production of alloys similar to modern brass, using copper and a zinc oxide-rich ore known as calamine, began around the 1st century BC.
Calamine brass was produced using a cementation process, whereby copper was melted in a crucible along with ground smithsonite (or calamine) ore. At high temperatures, zinc present in such ore vaporizes and permeates the copper, thereby producing a relatively pure brass with between 15 and 30 percent zinc content.
Not long after the Romans had discovered how to produce brass, the alloy started to be used in coinage in areas of modern-day Turkey. Brass coins soon spread throughout the Roman Empire, and there is evidence that calamine brass production moved into northern Europe under Rome's authority.
After the fall of the Roman Empire, localized production continued in Europe, but not nearly to the same extent.
Brass production on the Indian subcontinent also stretches back to the first century BC, and it is here where the process of 'speltering' brass is believed to have first developed. As opposed to the cementation process that produced calamine brass, speltering is a process that directly alloys metallic zinc with copper.
Speltering allowed brass makers to have greater control over the zinc content and, therefore, the properties of the brass alloy being produced. This process, however, depended upon the availability of metallic zinc, which was available in Asia centuries before it was seen in Europe.
With industrial production of metallic zinc occurring near Zawar, Rajasthan by the 14th century, it is believed that the first spelter brass was also produced here around this period.
To date, the earliest conclusive evidence of a speltered brass product is an astrolabe made in Lahore around 1600.
Back in Europe, prior to the arrival of silver and gold from the New World, brass was used as a precious metal to adorn church monuments and tombs.
Growing demand led to increasing production in Germany and Belgium during the 15th and 16th centuries, and by 1559 the town of Aachen in Germany reportedly had the capacity to produce more than 13,000 metric tons of brass per year. Meanwhile, documents from the same period show that large quantities of brassware were being shipped to West Africa, suggesting the development of international demand for brass.
Although zinc ingots from China and India were being shipped to Europe as early as the beginning of the 16th century, there is no evidence that metallurgists had made a connection between the zinc in calamine ore and zinc metal at that time.
There were numerous attempts to grow brass production in the UK from its first production at Tintern Abbey wireworks in 1568 until the abolishment of the Mines Royal Company in 1689. But it was not until after improvements to the purity of English copper were made in the early 18th century when brass making began to succeed in the areas around Bristol, Swansea, and Birmingham.
In 1738 William Champion patented a method for the industrial distillation of metallic zinc, which he produced in large quantities, but it was not until 1781 that a patent for speltering brass was granted to James Emerson. Although not initially widely accepted, mainly due to the cost of production, over the following 70 years speltering slowly replaced cementation as the main mode of production for brass alloys.
Prior to the industrial revolution, there were limited applications specifically suited to brass. One such use was, however, in pins for the wool industry. A brass rolling mill in Esher, Surrey, England that dates back to 1697, specialized in producing such pins.
Brass production in America commenced after independence and was driven by demand for brass buttons for military uniforms. During the 1800s, Waterbury, Connecticut developed a large brass-related industry, producing clocks, buttons, and lamps.
Brass's unique properties would soon result in it being used in the production of many technical instruments, such as clocks, watches, chronometers and navigational tools.
By the mid-19th century, newer and cheaper grades of the alloy, similar to today's free cutting brasses, were developed and found use as sheathing on the hulls of wooden ships. The Cutty Sark, a famed tea clipper that carried goods between England and Australia during the second half of the 19th century, was sheathed in Muntz metal, a 60/40 brass alloy patented in 1832.
Another major use for brass came with the development of metal ammunition cartridges in France around 1846.
Brass's ability to be rolled into thin, corrosion-resistant, non-magnetic and low friction sheets made it ideal for cartridge shells. The .44 Henry and .56-56 Spencer, used in rifles during the American Civil war, were both made from brass.
Kharakwal, J.S. and L.K. Gurjar. "Zinc and Brass in Archaeological Perspective." Ancient Asia Journal of the Society of South Asian Archaeology. URL: http://www.ancient-asia-journal.com/article/view/aa.06112/23
Pollard, Mark and Carl Heron. Archaeological Chemistry. RSC Publishing (1996).
Callcut, Vin. Brief Early History of Brass. Copper Development Association Inc. www.copper.org
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