In ancient times, brass and bronze were some of the oldest metals used to make tools, jewelry, artifacts, and coins. The most ancient tin alloy bronze dates back to 4500 BC. Most treasure hunters dream of finding old coins, artifacts, and tools.
Have you wondered if your detector “Can Metal Detectors for Brass and Bronze?” After all, they vary in sensitivity and quality, so can all metal detectors detect these metals?
Even though they don’t have the highest electrical conductivity, like copper and silver, metal detectors can still detect bronze and brass. These metals can react to the electromagnetic field produced by the detectors’ coil.
As metal detectors, we want our devices to detect every valuable metal when scanning a surrounding. So, in this article, we’ll answer the question, “Can Metal Detectors find Brass and Bronze?” We’ll also elaborate more on what they are and why they can react to the magnetic field produced by metal detectors.
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Can Metal Detectors Find Brass and Bronze?
The simple answer is yes; even though they have low electrical conductivity, you can still detect them with most metal detectors. But before we elaborate more on why and how these devices can detect these metals, we need to find out what these metals are. We must also understand why they are unique and valuable, especially for collectors.
After all, they’re the most popular copper alloys used for centuries to make relics, coins, and artifacts. Plus, they have evolved over the years to the perfect metals with different uses that they have today. So let’s learn more about these metals separately…
What is Brass?
Brass is a unique alloy of zinc and copper in proportions that can help achieve chemical, electrical, and mechanical properties. It resembles gold and Bronze, another copper alloy that includes tin instead of tin. Brass is an ancient metal used for decoration purposes thanks to its unique gold-like, bright appearance. (source)
People have used brass since prehistoric times, but it became more prominent in the post-medieval period. Before that, zinc vapor was not considered metal. In fact, the earliest brass may have been made by simply melting zinc-rich copper ores found in the mines. During the Roman period, people produced it from zinc minerals and metallic copper.
Due to its popularity, many know brass as yellow copper. And thanks to its sufficient supply, brass was used as coinage in Bithynia and Phrygia. In Asia, people used brass and zinc to make ancient coins that are currently very valuable.
Like most old metals, people use brass for many purposes, which is why it is still a top target for metal detectorists worldwide. Most soldiers during the world wars used brass knuckles which are pretty valuable, especially for collectors. You can also find some brass relics from some of the ancient ruins all over the globe.
Is Brass Magnetic?
The answer to this question is relatively straightforward; brass is a mixture of non-magnetic metals (copper and zinc). And when they mix, they create a non-magnetic compound; therefore, brass is not magnetic. So how does a metal detector locate brass medals?
If It Is Not Magnetic, Can My Metal Detector Detect Brass?
Like zinc, copper, and aluminum, brass interacts with moving magnets. (source) For instance, a brass pendulum can swing rapidly without magnetic fields. But as soon as a magnet passes nearby, the pendulum slows down; unfortunately, it doesn’t have the same effect on wooden plates. (source)
Therefore, while brass is a non-magnetic metal, it can react to magnetic fields. The movement of the magnet causes this effect, which creates an electrical current in brass, thereby reacting with the magnet. Remember, the coil functions by sending an electromagnetic field to the ground. In return, it receives the electromagnetic field from the brass.
The electric field from the brass created by the passing electromagnetic field doubles back to the metal detector’s coil, producing a sound or vibrating. And with a proper tool or a device with a pinpointer, you can trace its exact location.
What Is Bronze?
Another valuable and ancient non-ferrous metal that metal detector enthusiasts love is Bronze. Bronze is an alloy of tin and copper; sometimes, it may even contain zinc, nickel, manganese, or aluminum. (source)
Bronze may contain non-metals like metalloids such as silicon, arsenic, and phosphorus. Adding these non-metals or metals makes this copper alloy even harder than pure copper, known for its valuable properties like machinability, ductility, or strength. But modern copper usually is 12% tin and 88% copper.
The origin of Bronze can trace back to the Bronze Age when it was considered the hardest metal available. But the earliest bronze artifact was designed around 4500 BCE. The percentage of copper in ancient bronze artifacts varies between 67% and 95%, which is why ancient artifacts are durable.
When Did Tin Replace Arsenic as a Bronze Ingredient?
Originally, Bronze was made by mixing arsenic and copper, resulting in the creation of arsenic bronze. But over time, folks started mixing copper with tin to create tin bronze. And in the process, they discovered that tin bronze was superior and easier to work.
Plus, unlike arsenic bronze, tin didn’t produce toxic fumes during the refining process. Therefore, by the third century BCE, tin had replaced arsenic as the critical ingredient for refining bronze. (source) But since tin was rare, it resulted in considerable trade between nations, with the significant tin mines being in Cornwall, United Kingdom.
Over time making, Bronze became more challenging and more expensive to produce than wrought iron, which saw the end of the Bronze Age. But the Bronze Age left us with some of the most beautiful artifacts that archeologists are discovering to date.
Types of Bronze
As aforementioned, modern Bronze features 12% tin, but several types of Bronze in the markets have different alloy compositions. Some of the most popular ones include:
- Alpha bronze is a unique bronze alloy that includes an alpha-solid tin solution. The percentage of tin in alpha bronze ranges between 4% and 5%, and it’s used to make blades, springs, and coins.
- Commercial Bronze contains 10% zinc and 90% copper; architectural Bronze has 40% zinc, 3% lead, and 57% copper. Unfortunately, they’re also considered brass alloys.
- Plastic Bronze contains lead which plays a crucial role in its plasticity.
- Silicon bronze contains manganese, silicon, iron, zinc, copper, and lead. (source)
These different types of Bronze will react differently with the metal detector. With a suitable device, you can pinpoint its exact position.
Other common bronze alloys include phosphor bronze, manganese bronze, and aluminum bronze. Therefore, you need to test and determine which type of Bronze you have uncovered after finding your coins or artifacts.
Is Bronze Magnetic?
Generally, Bronze is a non-ferrous metal that is automatically considered non-magnetic. But there are certain bronze alloys containing nickel and iron with magnetic properties. Therefore, most metal detectors can easily detect bronze metals with iron and nickel.
Unfortunately, Bronze containing ferrous metals is quite rare. So you have a low likelihood of mistaking a ferrous metal-containing bronze with other magnetic metal alloys.
Regrettably, most bronze alloys, including modern Bronze, don’t contain ferrous metals. Most of the alloys contain 11% to 12% of tin. Most of these alloys are common and have been used to make several artifacts over the years.
So can they be detected by a metal detector? Generally, Bronze has very low electrical conductivity, just like copper and silver. Still, it can react to the electromagnetic field produced by the metal detector’s coil.
Most modern metal detectors can detect both ferrous and non-ferrous metals. On the other hand, the older models can only detect ferrous metals. Therefore, before you search for these metals, you should upgrade your device to the latest version.
Looking for some “How To” metal detecting articles? I’ve got you covered
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Can You Mistake Brass for Bronze?
Generally, Bronze and brass have the same base element, copper; therefore, they have several resemblances and feel. But they are different, especially with the number of metals used to make the many brass and Bronze alloys. And being non-ferrous metals, how would you determine which metal you have discovered?
Well, for a start, they have different colors. You must first consider the color of the medallion you have found. Bronze has a reddish brown color, while brass resembles gold in color. Brass is customarily muted yellowish, which makes it the best option for fixtures and furniture. However, their colors change when other elements are introduced into the mixture.
Fortunately, there is a way you can determine the exact identity of the alloys used to make the Bronze or brass. And one of the most effective options is testing their physical and chemical properties.
How to Determine if You Have Found Brass?
Generally, brass medallions tend to develop a small layer on their surfaces with time. It can be greenish thanks to exposure to oxygen and dirt for a long time. Still, in some cases, it can take up a different color depending on where it’s found. Therefore, even if your device has detected it, you may need to find out if you have found brass, Bronze, or iron.
Therefore, you should use a magnet to determine whether it’s ferrous or non-ferrous. If it’s not attracted to the magnet, it may be brass or Bronze. After that, you can clean the object and confirm the color underneath.
You can start with soap and water to clean the coins or medallion. You can also wash it with vinegar and then rub it for a few minutes to remove the tarnish. If it’s yellowish, it may be brass, but if it’s reddish brown, it could be Bronze.
Other Tests
Scratch Test
The next step is a scratch test; basically, brass scratches easily. So you can test this on a small part of the relic. If you find it and it scratches easily, it is brass. Next, you can mark it on a ceramic surface; if it leaves a black line, it could be brass. (source)
Acid Test
Finally, you can pour a small amount of concentrated acid on your find and examine the reaction. Generally, you should know that gold doesn’t react if you compare it to gold. On the other hand, with brass, you’ll notice discoloration or bubbling in the place where you have placed a few drops of the acid. (source)
How to Test for Bronze at Home
Like brass, Bronze also tarnishes with time, so you should first clean it with vinegar and salt. The paste will serve as a scrubber that you can use to clean your find before rinsing it off using hot water.
If the color underneath is reddish brown, then it could be Bronze. You can do the above tests to confirm that it’s Bronze, not brass or any other metal. (source) These tests are affordable, and you can do them in the comfort of your home.
If you’re still unsure, you should take it to a professional and have it tested. Remember, professionals can tell you the ingredients you found to make the bronze alloy. A professional can even help you name the bronze alloy you have discovered and its exact value in the market.
Final Verdict
Despite being some of the oldest metals on the planet, Bronze and brass are non-ferrous metals thanks to the ingredients used to make them. Therefore, most people assume that metal detectors can’t detect them, which is not valid. After all, some modern metal detectors are designed to detect both magnetic and non-magnetic metals. Unfortunately, that’s different with older models. Plus, you may have to do several tests to determine if you have found a bronze or brass coin, artifact, or relic.
David Humphries, Writer and Creator of METAL DETECTING TIPS. After borrowing my son’s detector and finding $.25. I felt like a treasure hunter. FREE MONEY! I was seriously bitten by the metal detecting bug.
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Sources
- Wikipedia contributors, brass, https://en.wikipedia.org/wiki/Brass#Types/ accessed November 23, 2022.
- Is brass magnetic? https://terpconnect.umd.edu/~wbreslyn/magnets/is-brass-magnetic.html/ accessed November 23, 2022.
- YouTube contributor, Brass Pendulum and Lenz’s Law, https://www.youtube.com/watch?v=38XPT9sWIso/ accessed November 23, 2022.
- Wikipedia contributor, Bronze, https://en.wikipedia.org/wiki/Bronze#History/ accessed November 23, 2022.
- Jerry Ehrenwald, How to tell gold from brass, https://www.wikihow.com/Tell-Gold-from-Brass/ accessed November 23, 2022.
- Jessica Gibson, How to tell Bronze from brass, https://www.wikihow.com/Tell-Bronze-from-Brass/ accessed November 23, 2022.