Exploring metal supplies – What is brass?
Brass is an alloy which blends copper and zinc in a variety of proportions to create a range of different brasses, each with its own special properties. It’s a substitutional alloy, which simply means that the atoms of the two ingredients can replace each other in the same crystalline structure. Brass can also contain small amounts of arsenic, phosphorus, aluminium, manganese or silicon.
The ancient history of brass
Brass has been used for thousands of years. The old English word ‘brass’ can mean any bronze alloy, or copper, and the earliest versions of the metal were probably perfectly natural alloys created by smelting zinc-rich copper ore. The Romans made brass using copper and zinc minerals via the cementation process, a technology that lasted well into the 1800s. Another method, called speltering, involved copper and zinc metal being directly alloyed, something that was introduced to Europe in the 1500s. The famous Benin bronzes, some of the most magnificent and sophisticated African tribal art, are actually made from a lead-rich zinc brass.
How do you tell if it’s real brass?
It’s easy to identify genuine brass, simply because a magnet won’t stick to it. If your magnet sticks, it means you’re probably dealing with a piece of brass-plated steel or iron.
How to clean brass
A proprietary brass cleaner is good. But you can also clean brass using ketchup, Worcestershire sauce, yoghurt, white vinegar or a blend of milk and water, all of which contain the right kind of acids.
What is brass used for?
Brass is frequently used as a decorative metal because of its lovely gold-like shine. It’s perfect in low friction environments like locks, knobs, screws, valves, gears, bearings and ammo casings, and it’s often harnessed in plumbing and electrical applications. It’s traditionally used to make brass musical instruments too, combining easy workability with great strength, impressive durability and excellent acoustic properties.
It’s also commonly seen in applications where a spark or flame could be lethal, for example tools for use in environments where there are flammable or explosive materials. Brass is strong, beautiful, malleable, resistant to corrosion and able to withstand extreme temperatures. It’s also great for casting, easy enough to melt down and try again if things go wrong.
Brass and stress corrosion
Brass is vulnerable to cracking through stress corrosion cracking, particularly when ammonia and substances containing or releasing it are around. It’s often called ‘season cracking’ thanks to rotting brass bullet cartridge cases used in British Indian Army rifles during the 1920s. When they were stored in stables, close to ammonia from concentrated horse urine, brittle cracks appeared. The issue was solved by annealing the cases – in other words heating them then letting them cool down slowly – and storing the cartridges away from horses.
What is DZR, CR or DR brass?
You may have heard of dezincification resistant brasses, sometimes called corrosion resistant, perfect when there’s a high risk or corrosion and standard brass doesn’t fit the bill. Very hot water, chlorides and very soft water can damage ordinary brasses but the DZR types, while tricky to produce, are formulated to avoid long-term failure.
Brass as an anti-bacterial material
People have known about brass’ anti-bacterial properties for hundreds of years. It’s brilliant in marine environments, for example, where the copper in the metal works to kill micro-organisms remarkably quickly, often within minutes. It is even thought to play a part in combating the hospital ‘superbugs’ MRSA and VRSA.
Different types of brass
• Alpha brass is malleable. You can work it cold. It’s often used in pressing and forging and contains a high proportion of copper giving it a more golden colour than other brasses.
• Alpha-beta brass, AKA duplex brass, is perfect for hot work. It contains a higher proportion of zinc which makes it look brighter and shinier than alpha brass.
• Beta brass is perfect for hot work, and it’s both harder and stronger than the rest so ideal for casting. It comes with high zinc and low copper, making it the brightest and least gold-coloured than the rest.
• White brass is far too brittle for most uses, with more or less no yellow colour.
You need to ask questions about brass? No problem
If you have any questions abour the applications brass can be used for, its compositrion, the best type to use and what kinds of brass sheet we supply, we’ll be delighted to help.
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