Brass is a metal alloy composed of zinc and copper, known for its warm golden hue and numerous unique properties. It has a rich history and many modern applications including jewelry, sculpture, coinage, instruments, and machinery. Read on for MKM Jewelry’s breakdown of brass metal properties.
A Brief History of Brass
Earliest Examples in Asia
The earliest examples of brass date back to the 5th century BC in China. The brass artifacts that have been found are only 5% to 15% zinc, which indicates that they might be made from “natural alloys” and could have been created unintentionally. Most likely these metals were smelted from a zinc rich copper ore, resulting in an unintentional brass-like metal. Some relics however, are known to be deliberately manufactured and have the golden coloring distinctive to brass.
Examples of other copper-zinc alloys began appearing across the Middle East and Asia in the 3rd century BC. Brass from this time period has been found in the United Arab Emirates, West India, Uzbekistan, Iran, Syria, and Iraq. Through trade with the Middle East, brass usage began to spread across the world, from Britain and Spain to India.
Brass Production in the Roman Empire
Archaeologists have discovered evidence that the Greeks and Romans were intentionally making brass alloy by the 1st century BC. The Romans created calamine brass through a process known as cementation, where copper and calamine, a zinc rich ore, are heated together until the zinc becomes a vapor, which reacts with copper to create a brass alloy. Brass was used by the Romans to make coins and other artifacts.
Soon after these advances in brass production by the Romans, Turkey began to make currency from brass as well. Brass began to spread across the Roman Empire, all the way up through Northern Europe. Before silver and gold became available from North and South America, brass was considered a precious metal and was used for ornamental purposes in churches and tombs.
Speltering in India
Brass also began to appear in India in the 1st century BC. Unlike Roman calamine brass, Indians did not use cementation to produce brass, but rather a process called speltering. Speltering gives brass producers greater control over the zinc content of the brass, and thus adjust the brass metal properties.
Brass in Africa
In Africa, brass was used in much of the art in the region. Although frequently referred to as bronzes, many of the Nigerian lost wax castings, including the famous Head of Queen Idia, are actually cast in brass. Brass was frequently used in African sculpture, as it was considered to be more valuable there then it was in Europe.
Brass’s Growing Presence
After the Industrial Revolution, the number of brass uses began to multiply. In America, brass was increasingly popular for buttons on military uniforms, and the market expanded to include brass lamps and clockwork.
Brass metal’s properties as a corrosion resistant, non-magnetic, and low friction material made it the ideal choice for metal ammunition cartridges in France in 1846. Two of the most common rifle bullets used in the American Civil war were made from brass as well.
But What Is Brass?
As a zinc-copper alloy, there are many different types of brass, dependent on the concentration of the different metals in the alloy. There are 60 different types of brass ranging from Abyssinian gold, which is 90% copper, to Delta Metal, which only has a concentration of 55% copper.
The varying concentrations of zinc and copper give the different types of brass a wide color variation and an array of brass metal properties. Brass with higher copper proportion are a reddish brown color, while brass with a higher zinc concentration take on a lighter silvery yellow hue. Some types of brass also have low percentages of other elements added, including silicon, aluminum, manganese, and nickel.
The chemical composition of brass will cause it to tarnish over time when exposed to the air. This particular property of brass metal can be utilized to create beautiful patinas, which are thin layers of color that protect the metal and give it a rich, antique look. The original golden surface of brass can be maintained through regular polishing.
The Three Classes
There are three basic crystal structures for brass, which lead to the three main classes:
Alpha brasses have a copper concentration of over 65%. They have a face-centered cubic crystal structure, and can be worked cold. This makes alpha brasses ideal for pressing and forging. Alpha brasses are also the most golden of the different brasses, due to their high proportion of copper.
Alpha-beta brasses are alloys that are between 55-65% copper and 35-45% zinc. The higher concentration of zinc gives these brass metals bright, shiny properties. They contain both face-centered cubic crystals, and body centered cubic crystals. This makes Alpha-beta brasses stronger than Alpha brasses, and they are usually worked hot.
Beta brasses are alloys that are between 50-55% copper and 45-55% zinc. They are the hardest, strongest brasses, and must be worked hot. Beta brass is ideal for casting. Because of its high zinc content, and low proportion of copper, beta brass is the least golden of the three classes of brass.
Properties of Brass Metal
Brass is a more malleable material than either bronze or zinc, making it easy to manipulate. One of the most notable brass metal properties is its relatively low melting point, at 900-940° Celsius. Its low melting point and strong flow makes it an easy metal for casting. Brass is known for its machinability, because it can be easily worked and shaped while maintaining its strength.
In terms of physical properties, brass is a good conductor for both heat and electricity. One of the most special brass metal properties is its antimicrobial nature, making it a good choice for bathroom fixtures and fixtures in healthcare facilities.
Nearly 90% of today’s brass alloys are recycled. Brass is not ferromagnetic, so brass scrap can be separated from ferrous scrap using a powerful magnet. This brass scrap can be melted and cast into billets to be recycled.
New brass is produced from copper scrap and zinc ingots. Copper’s boiling point is lower than zinc’s, so the copper is melted first, and zinc is added to the already molten metal afterwards. Some of the zinc is lost to vaporization, but the remaining zinc reacts with the copper to create a brass alloy. Any other additions, such as lead, aluminum, tin, or silicon, are added to the mixture at this time.
The molten alloy is poured into slabs or billets, which can be extruded into tubes and wires, or rolled into sheets. A thin layer of raw material is trimmed off by a milling machine, to remove imperfections from casting and oxide. The brass is then heated, gas treated, and rolled again, in a process known as annealing. Brass is then cold rolled repeatedly, which increases the brass metal properties of strength and hardness by deforming the inner grain structure of the metal.
Finally, the new brass is soaked in a chemical bath of hydrochloric and sulfuric acid in order to remove tarnish and oxidation.
Today, brass is considered a versatile metal with many different uses, including jewelry, sculpture, musical instruments, as well as a variety of industrial applications.
Jewelry and Art
Many jewelers enjoy working with brass for its aesthetic qualities and relative affordability. An easy metal to cast, brass is often chosen for intricate lost wax castings. Brass’s attractive golden hue makes for striking jewelry, at a much lower price point than gold.
In art, both historic and modern artists have used brass to cast sculptures. Besides casting, brass can be worked both hot and cold, making it a favorite for metalsmiths to sculpt with.
Perhaps the most famous brass use is its role in the making of musical instruments. The brass instrument family includes trumpets, tubas, trombones, French horns, and more. Because brass is very malleable, it is easy to make the long narrow tubing, which is used in horn instruments. In addition, brass metal’s properties of resistance to corrosion and strong acoustic qualities, as well as its economic price point, makes it an attractive choice for manufacturing instruments.
Besides traditional brass instruments, woodwind instruments such as saxophones are also frequently made of brass, for similar reasons. Brass is used for the production of percussion instruments such as cymbals, gongs, and hand bells as well.
In an industrial context, free cutting brass is commonly used for screw machine stock. Brass metal’s properties as a corrosive resistant alloy, with a smooth finish makes it ideal for machining. Free cutting brass is used in nuts, bolts, threaded parts, plumbing fitting, adapters, jets, taps, and more.
Naval brass has a composition that is 59% copper, 40% zinc, 1% tin, and also contains traces of lead. The resulting alloy is has great machinability, and is very resistant to corrosion, making it ideal for marine hardware.
Brass Finishes for Jewelry and Art
There are many brass uses in different styles of art and jewelry. Matte brass has a soft, frosted effect for a muted, understated finish. Brushed brass has a similarly soft finish, with a bright, warm tone, and an interesting brushed textural surface. Stone finish brass has an earthy rugged finish for a touch of bold texture. For those seeking the ultimate shine factor, look for high polish brass, which has a sparkling, golden finish.
MKM Jewelry offers a number of different finishes for brass including:
Raw Eco Brass
Stone Finished Brass
High Polished Brass
MKM Jewelry Creations
At MKM Jewelry, we can help you produce a run of jewelry or a special custom piece that showcases both the beauty of your design, and richness of brass. Our team of industry professionals are here to help you bring your creative vision to life. From high-tech CAD and CAM services and mold making to experienced casting and engraving, MKM Jewelry has worked brass into jewelry, art, and more! MKM Jewelry can also add gold, silver, or rhodium plating to your brass base piece for a stunning effect.
Brass is a beautiful, versatile metal, with many properties that make it a great choice for jewelry production. Partner with MKM Jewelry to manufacture your next design and learn how brass metal properties can benefit you!