Two of the most common “red” metal alloys are bronze and brass. Many people think they are interchangeable and commonly confuse the two. While they are very similar, both are based out of copper, they have some distinct differences you should know.
I’m not going to get into all the different metallurgic properties of brass vs. bronze in this post but I do want to give you an overview and by the end of this post you should be better able to tell the difference between brass and bronze.
What is Bronze?
You’ve heard of the Bronze-age, right? Well, around 4500 BC humans discovered that if you mixed copper with tin you get a stronger metal that can be worked into tools and weapons. This discovery changed the course of human history.
Bronze is an alloy of copper and tin often mixed with other metals to get slightly different properties. Primarily bronze is a mix of 88% copper and 12% tin resulting is a deep red or bright brownish metal.
Bronze is also sometimes mixed with other elements to change its composition and properties like arsenic, phosphorous, aluminum, manganese, silicone, and nickel.
Bronze has been used for millennia for all sorts of applications. From statues to coins, building materials, nautical applications, mechanical parts, hardware, the list goes on.
Bronze is extraordinarily resistant to corrosion and can be used on boats or other coastal applications subject to saltwater.
One popular use for bronze is in window and door weatherstripping called spring bronze which is usually a phosphor bronze blend and solid bronze nails. This weatherstripping is extremely durable, even in coastal areas, and can last centuries.
It’s low melting point of around 950°C and easy machinability make it excellent for many applications. It is still widely used today for springs, bearings, bushings, automobile transmission pilot bearings, and similar fittings due to its low friction against other metals.
One interesting thing about bronze is that unlike steel it doesn’t produce a spark when struck against hard surfaces. This makes it an ideal metal to use in applications where there is a high risk of flammability or explosions.
What is Brass?
Brass is an alloy of copper and zinc though it can be mixed with other metals in addition. Most brass is made with a mix of 34% zinc and 66% copper. Brass is typically a dull gold colored metal that is extremely workable and has a relatively low melting point of around 900°C.
Brass was discovered much later than bronze, around 500 BC and at first the discoveries were called “mountain copper“ which were naturally occurring mixtures of copper and zinc that when melted down formed a golden metal. These early mixtures were usually between 5% to 15% zinc, much lower than modern alloys.
Brass provides good corrosion resistance, aging to a deep copper color and eventually forms a green patina (my favorite color!) that is protective of the subsurface brass unlike with steel or iron.
Brass provides excellent anti-microbial qualities like copper. It has been found that 99.9% of microbes left on a brass or copper surface were killed within 2 hours. That makes brass a great material for things like door handles and other hardware that gets daily use.
It’s low friction and lack of corrosion makes brass one of the tip choices for moveable parts of hardware like hinges, locks, and latches as well as being the first choice for instruments which need a strong yet workable metal with excellent resonance.
How to Tell the Difference
Without doing a chemical analysis of the metals the best way to distinguish the difference of brass vs. bronze is by their color. Brass will usually be a dull gold color and bronze has a more reddish or copper color.
Of course the colors can also change slightly between castings because of the percentage of copper used in each batch. Since brass and bronze can have variety in their percentage of copper you can have some brasses that are less gold and more copper color and the same goes for bronze.
Another way to test to see if you are dealing with brass or bronze is to use a magnet on the metal. Neither brass nor bronze are magnetic so if the metal responds to a magnet then you know it is steel or iron and not brass or bronze.
Brass is more ductile and malleable than bronze which is a more brittle metal comparatively. If the metal bends without breaking then chances are you’ve got brass.
While both metals are resistant to corrosion, bronze provides much better protection. This is another way to determine the difference between the metals. Soak both metals in a bath of salt water or an aging solution and bronze will age much more slowly than the brass will.
Hopefully, you’ve got a good sense of the difference between brass vs. bronze now and you can look out for the two to see if you can spot which metal is which. Happy hunting!
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I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.