After the Copper (Chalcolithic) Age came the Bronze Age, followed later by the Iron Age. There was no 'Brass Age' because, for many years, it was not easy to make brass. Before the 18th century, zinc metal could not be made since it melts at 420ºC and boils at about 950ºC, below the temperature needed to reduce zinc oxide with charcoal. In the absence of native zinc it was necessary to make brass by mixing ground smithsonite ore (calamine) with copper and heating the mixture in a crucible. The heat was sufficient to reduce the ore to metallic state but not melt the copper. The vapor from the zinc permeated the copper to form brass, which could then be melted to give a uniform alloy.
Only in the last millennium has brass been appreciated as an engineering alloy. Initially, bronze was easier to make using native copper and tin and was ideal for the manufacture of utensils. Pre-dynastic Egyptians knew copper very well and in hieroglyphs copper was represented by the ankh symbol 'C' also used to denote eternal life, an early appreciation of the lifetime cost-effectiveness of copper and its alloys. While tin was readily available for the manufacture of bronze, brass was little used except where its golden color was required. The Greeks knew brass as 'oreichalcos', a brilliant and white copper.
Several Roman writers refer to brass, calling it 'Aurichalum.' It was used for the production of sesterces coins and many Romans also liked it especially for the production of golden colored helmets. They used grades containing from 11 to 28 per cent of zinc to obtain decorative colors for all types for ornamental jewelry. For the most ornate work the metal had to be very ductile and the composition preferred was 18%, nearly that of the 80/20 gilding metal still in demand.
As mentioned, in medieval times there was no source of pure zinc. When Swansea, in South Wales, was effectively the center of the world's copper industry, brass was made in Britain from calamine found in the Mendip hills in Somerset. China, Germany, Holland and Sweden had brass making industries with good reputations for quality. Brass was popular for church monuments, thin plates being let in to stone floors and inscribed to commemorate the dead. These usually contained 23-29% of zinc, frequently with small quantities of lead and tin as well. On occasions, some were recycled by being turned over and re-cut.
One of the principal industrial users of brass was the woolen trade, on which prosperity depended prior to the industrial revolution. In Shakespearean times, one company had a monopoly on the making of brass wire in England. This caused significant quantities to be smuggled in from mainland Europe. Later the pin trade became very important, about 15-20% of zinc was usual with low lead and tin to permit significant cold working to size. Because of its ease of manufacture, machining and corrosion resistance, brass also became the standard alloy from which were made all accurate instruments such as clocks, watches and navigational aids. The invention by Harrison of the chronometer in 1761 depended on the use of brass for the manufacture of an accurate timekeeper that won him a prize of ï¿½20,000. This took much of the guesswork out of marine navigation and saved many lives. There are many examples of clocks from the 17th and 18th centuries still in good working order.
With the coming of the industrial revolution, the production of brass became even more important. In 1738, William Champion was able to take out a patent for the production of zinc by distillation from calamine and charcoal. Cast brass was hammered to make wrought plate in a water-powered 'battery'. Rods cut from the plate were then pulled through dies by hand to make the vital stock needed for pins for the textile weaving industry. Although the first rolling mills were installed in the 17th century, it was not until the mid-19th century that powerful rolling mills were generally introduced.
In America, one of the first recorded brass founders and fabricators is Joseph Jenks in Lynn, Mass from 1647 to 1679 with brass pins for wool making being a very important product. Despite legal restrictions, many others set up such works during the eighteenth century. (Schiffer, P. et al, The Brass Book, 1978, ISBN 0-916838-17-X).
With the invention of 60/40 brass by Muntz in 1832 it became possible to make cheap, hot workable brass plates. These supplanted the use of copper for the sheathing of wooden ships to prevent biofouling and worm attack.
With improvements in water communications, trade became easier and production could be sited near to fuel supplies and routes to facilitate central distribution round the country. In 1894, Alexander Dick invented the extrusion press that revolutionized the production of good quality low-cost rods. Subsequent developments in production technology have kept pace with customers' demands for better, consistent quality in products produced in large quantities.
Author: Vin Callcut