Brass

Brass is the name used to describe a number of metal alloys, all combinations of copper and zinc, but with different properties depending on their zinc content (which can vary from 5% to 45%). Examples of early copper-zinc alloys have been found in West Asia and the Eastern Mediterranean dating back to about 3000BC, but it was the Romans that really spread this material around the world. Brass, which the Romans called orichalchum, appears in the archaeological record in the 1st century BC in Europe. Orichalcum was used to make military equipment and some coinage under Julius Caesar, though this then halted until the monetary reforms of Augustus dictated that this material must be used to make dupondii and sestertii coins. Perhaps because of its gold-like appearance and relative resistance to tarnishing, brass has often been used for coinage since then. The old £1 coins were made entirely from nickel-brass, but the new ones use it only in the gold outer ring.

This sample of brass is an attractive, shiny, yellow-gold metal with a brownish layer of patination. The colour of brass can vary from red to chocolate brown depending on the composition of the alloy and amount of weathering. Because of their colour and other aesthetic qualities, brasses are often used in decorative applications, for example in architectural hardware – doorknobs, handrails, etc. Brass is also relatively easy to cast and has good acoustic properties, so has become the material of choice for many musical instruments. It is not only used to make ‘brass instruments’ like the trombone and French horn, but also some wind instruments like the saxophone. Because of the high copper content of brass, it has naturally antibacterial qualities. Because these instruments are played with the mouth, brass is normally preferred to stainless steel or aluminium, which have good sound qualities but are quickly colonized by microorganisms.