Brass and bronze are two copper alloys. Brass is a copper and zinc alloy, while bronze is a copper and tin alloy. But, it’s not always easy to tell them apart. Here is a look at what brass and bronze are made of and their properties.
Brass is an alloy of copper and zinc, while bronze is an alloy of copper and tin. But, there is so much overlap between their compositions it’s more accurate to just call them copper alloys!
What Is Brass?
Brass is an alloy of copper and zinc, often with other elements, including lead, arsenic, phosphorus, silicon, manganese, and aluminum. It is a substitutional alloy. This means zinc atoms replace copper atoms within the crystal structure.
Modern brass is 67% copper and 33% zinc. However, there are types of brass with copper ranging between 55% and 95% by weight, with zinc ranging between 45% and 5%. Some types of brass contain around 2% lead. Lead improves brass machinability, but the toxic metal readily leaches from the alloy. This occurs even when the alloy contains a low concentration of lead.
Properties of Brass
Brass displays several characteristic properties.
- Brass color depends on its composition. Brass may be golden, copper-colored, or silver-colored. A higher percentage of copper yields a rosy tone, while a higher zinc concentration makes the metal silvery.
- The metal exhibits low friction.
- It’s easy to cast into shapes using molds.
- Brass is more malleable than bronze or zinc.
- Brass has desirable acoustic properties that make it a great choice for musical instruments.
- The alloy is a soft metal that has a low chance of sparking against other metals.
- Brass is a good heat conductor.
- It has a relatively low melting point for a metal.
- Brass resists corrosion, including galvanic corrosion in seawater.
- Brass isn’t ferromagnetic. One consequence is that it’s easy to separate from magnetic metals for recycling.
Brass has many uses. These include:
- Musical instruments
- Door knobs
- Decorative items
- Architectural trim
- Costume jewelry
- Pipes and tubing
- Firearm cartridge casings
How to Clean Brass (and Bronze and Copper)
Of course, there is commercial brass polish available, but it’s easy to make brass cleaner yourself using common household ingredients. The polish works for bronze and copper, too.
- Juice from half a lemon
- 1 teaspoon baking soda (sodium bicarbonate)
Mix the lemon juice and baking soda together to form a thick paste. Apply the paste to the discolored metal and allow it to sit for up to 30 minutes. Rinse the metal with warm water and let it dry.
Mix together equal parts of flour and salt. Add enough vinegar to make a thick paste. Apply the paste to the metal. Let the cleaner react with the metal up to 30 minutes. Rinse with warm water and let dry.
- 1 tablespoon salt
- 2 tablespoons vinegar
- 1 pint water
Either soak the metal in the liquid or else wipe it onto the surface using a soft cloth. This recipe works best if it’s heated before use. After cleaning, rinse with water and let dry.
Acidic ingredients (ketchup, salsa, fruit juice, or Worcestershire sauce) also work as brass cleaners. Gel toothpaste works, but avoid gritty toothpaste because it can scratch the metal surface.
The common names for the various types of brass don’t always indicate their composition, so the Unified Numbering System for metals and alloys is the best way to identify brass. The alloy name starts with the letter “C” to indicate it is a copper alloy. Five digits follow the letter. Wrought brasses, suitable for mechanical forming, begin with 1 through 7. Cast brasses, formed by molding molten metal, contain the digit 8 or 9.
What Is Bronze?
Like brass, bronze is a copper alloy. The difference is that it contains tin in place of zinc. Other elements in bronze include arsenic, lead, aluminum, phosphorus, silicon, and manganese.
Difference Between Brass and Bronze
While there is some overlap between brass and bronze, they are two distinct alloys. Here’s a look at the difference between them:
|Composition||Copper and zinc alloy that may contain iron, manganese, silicon, aluminum, or other elements.||Usually an alloy of copper and tin, but may copper with manganese, silicon, phosphorus, or aluminum.||Pure element|
|Color||Golden, coppery, or silvery||Usually reddish like copper and not as bright as brass.||Copper (reddish)|
|Properties||More malleable than copper or zinc. Corrosion resistant. Not as hard as steel. Susceptible to stress cracking from ammonia exposure. Relatively low melting point.||Better thermal and electrical conductor than many steels. Brittle, hard, resists fatigue. Corrosion resistant. Usually a higher melting point than brass.||Better thermal and electrical conductor than brass or bronze.|
|Uses||Musical instruments, plumbing, decoration, low-friction applications (e.g., valves, locks), tools and fittings used around explosives.||Bronze sculpture, bells and cymbals, mirrors and reflectors, ship fittings, submerged parts, springs, electrical connectors.||Electrical equipment, plumbing, roofing, heat exchangers.|
|History||Brass dates back to around 500 B.C.E.||Bronze is an older alloy than brass, dating back to about 3500 B.C.E.||Known to ancient humans, at least as early as 8000 B.C.E.|
- Craddock, P. T.; Lang, J. (2003). Mining and Metal Production Through the Ages. British Museum Press. ISBN: 978-0714127705.
- Gayle, Margot, et al. (1992). Metals in Americas Historic Buildings: Uses and Preservation Treatments. Diane Publishing Co.
- Tylecote, R.F. (1992). A History of Metallurgy (2nd ed.). London: Maney Publishing, for the Institute of Materials. ISBN 978-1-902653-79-2.