Whether you are a home hobbyist, a furniture or fixtures prototyper or have the interests of a small workshop to look out for, it never hurts to know a bit more about your materials. In this case, we’re comparing copper and brass from the ‘maker’s perspective’.
Well, let’s start at the beginning.
What is Copper?
Copper is a soft, reddish metal with excellent electrical conductivity. It was one of the first metals humans learned to work, and before the ‘bronze age’, it was the metal for making hard or sharp tools and weapons. It is a pure element, not an alloy, and often appears in nature in its elemental state – a rarity among metals.
What is Brass?
Brass is an alloy of copper – copper with other metals mixed in. Specifically, it isn’t brass unless it also has a high proportion of zinc. It may also bear small amounts of arsenic, lead, phosphorus, aluminium, manganese and/or silicon, either as an unavoidable side effect of its manufacture or to give the brass special properties. For example, corrosion-resistant brass contains between 1.7 and 2.8% lead, and up to 0.15% arsenic.
Now, let’s compare the 2 metals on 7 key factors:
Copper is the industrial standard for electrical conductivity, and it makes up almost all of the electrical wiring around you.
Brass is still a conductive metal, but it has a much higher resistance or impedance than copper. Most brass alloys are only 25-30% as electrically conductive as copper.
Neither metal contains iron, so technically neither will ‘rust’. Copper corrodes easily, though, building up a green patina. Brass is much more resistant to corrosion than copper, even if it isn’t an especially corrosion resistant formulation.
Machinability is a gauge of how easily a material can be cut, milled, die-cast, etc. It is a very hard concept to put a number on, as it can be measured for each type of process. However, across the board, brass is more machinable than copper.
Copper is easier to weld than any type of brass. That said, you can fairly easily weld brass, so long as it contains no lead. Brass with 20% zinc or less – which is closer to being copper – welds better than high-zinc brass.
Copper also has a very high thermal conductivity – it transmits heat from a ‘hot’ side to a ‘cold’ side very easily. Copper’s thermal conductivity is expressed as 223 BTU/(hr·ft⋅°F. To non-engineers, that is a lot.
Brass is still fairly thermally conductive, at 64 BTU/(hr·ft⋅°F, but nowhere near that of copper. It makes a poor heat exchanger. As an alloy, thought, brass’ thermal conductivity does rise as its temperature goes up.
If you’re going to cast something to use in the cold, all else being equal, a low melting point is your friend. If you’re going to machine or work something to use in a hot environment, a high melting point is better. (Pro-tip, all else is never equal).
Copper melts at 1084°C. Brass melts at anywhere from 900°C to 940°C, depending on its exact composition. The difference isn’t great, but it might be important.
Now we’re down to brass tacks, literally.
Copper is fairly expensive, more so than most of the materials you can alloy it with to produce brass. Therefore, brass will almost always be less expensive than pure copper.
Did that answer all possible questions? No, of course not. But it is a start. If you have any questions about the properties of any of our metal products or their suitability for your projects, please contact us today at T: 0151 294 6202 We’ll be happy to help.