Metal detecting is a thrilling and interesting way to gather various objects made with different metals, and many people assume that detectors can successfully detect all metal. However, these tools have limitations, and some metals are extremely difficult to detect.
A metal detector can detect all kinds of metal if there is enough of it. However, most metal detectors won’t detect stainless steel, titanium, brass, or lead because these metals have little to no magnetic properties and low electrical conductivity.
This article will explore the metals that a metal detector won’t detect in great detail. I’ll explain why these metals are more difficult to detect and if there’s anything you can do to increase your chances of detecting them. Let’s get started!
1. Stainless Steel
It is not impossible for a metal detector to detect stainless steel. If there is a large enough sample, and you have a high-quality metal detector, you’ll probably be able to get some sort of signal from your detector. However, in most cases and with most metal detectors, you won’t be able to detect stainless steel.
Stainless steel is an alloy that is primarily made of iron and chromium, along with other additives such as:
These additional elements give stainless steel its desirable corrosion-resistant qualities, which makes materials made with stainless steel last longer and stay rust-free. For this reason, lots of jewelry is made with stainless steel, and some tools and other interesting items you may want to find with a metal detector. Unfortunately, these same elements make stainless steel nearly impossible to detect with a metal detector.
It is difficult to detect stainless steel with a metal detector because the material is a poor electrical conductor. Electrical conductivity measures electricity’s ability to go through a certain material or object.
Electricity and magnetism go hand in hand, so if a material has poor electrical conductivity, it will also have poor magnetic qualities, making it difficult for a metal detector to detect.
Metal detectors do not have magnets inside them, but they rely on electromagnetism to work. Our understanding of electromagnetism comes from James Clerk Maxwell, who wrote that when there’s a change in an electric field, a change in the magnetic field will follow, and vice versa.
When the battery in your metal detector sends electricity through the inductor coil, it creates a magnetic field around the coil. When this magnetic field encounters a metal, it will interact with the electrons inside the metal, creating electric currents.
Usually, this interaction between the magnetic field and the metal object is enough to create a magnetic field and another electrical current that goes through the receiver coil, signaling the metal detector to give off an alarm that it has detected something. However, if a metal has poor electrical conductivity, this process either doesn’t happen, or the current isn’t strong enough to trigger a response from the metal detector.
Stainless steel has an electrical conductivity of 1.28 x 10E6 siemens per meter, which is quite low compared to silver, the metal with the highest electrical conductivity, with 62.1 x 10E6 siemens per meter.
Stainless steel is a metal, so technically, a metal detector can detect it. If you were to wave a metal detector over a large amount of stainless steel, you’d probably get some sort of response. However, the pockets of stainless steel you come across worldwide are rarely, if ever, large enough for a metal detector to detect.
With the right metal detector, it is possible to detect stainless steel. I recommend using a device not designed for gold because most prospecting metal detectors discriminate against steel, brass, and iron objects.
Instead, if your goal is to detect stainless steel, I recommend using a metal detector adept with low frequencies.
One device is the Garrett AT Pro Metal Detector (available on Amazon.com). Not only is this metal detector great with low frequencies, but it also features advanced and proportional audio modes that allow the user to hear subtle changes in the response signal, which gives them a better idea of what to expect before digging. I also like that it can reach a depth of ten feet (3.05 m).
Some stainless steel items you might find while metal detecting include:
- Large pieces of jewelry. Lots of jewelry is made of stainless steel because it doesn’t rust or cause the greenish color on the skin that many cheaper materials cause. However, it will be difficult for a metal detector to detect small pieces, such as earring studs, so chances are higher that you’ll find bigger items, such as necklaces or bracelets or large, chunky rings.
- Cookware. It is common for cutlery and utensils to be made of stainless steel, and most of these objects are large enough for a metal detector to sense them. If you’re lucky, you may end up digging up an older fork or a knife with fascinating designs or engravings! You’ll also probably have luck if you’re on an abandoned building site.
- Garden equipment. Many modern gardening tools are made of stainless steel, including rakes, hand scoops, hand transplanters, trowels, tillers, and more. Many of these items are relatively large, so your metal detector should be able to detect them. And because these tools are used outside, you’re more likely to find them when you’re out and about metal detecting!
- Surgical tools. Many surgical tools, including forceps, tweezers, scissors, and blades, are made with high-quality stainless steel for ultimate safety and cleanliness. Modern and high-quality metal detectors should be able to detect these items, even though some are pretty small.
Ultimately, while a metal detector can detect stainless steel, it is highly unlikely, and you shouldn’t have high hopes for your chances of scoring a stainless steel find.
Like stainless steel, titanium is a relatively non-magnetic metal, making it more difficult for metal detectors. However, metal detectors with advanced technology can usually pick up on this metal if the detector is in the right setting or if the titanium is mixed with a more magnetic metal like silver. Titanium is used as an alloy in many jewelry items, so it’s not unusual to find a piece of jewelry containing titanium while metal detecting.
Even with the best metal detector, it is extremely difficult to detect titanium in highly mineralized or wet ground conditions. Normally, metal detecting in the rain isn’t an issue and has some benefits, but I don’t recommend this practice if you want to find titanium.
Here are some titanium objects you may find with a high-quality metal detector and in ideal conditions:
- Jewelry. As mentioned above, titanium is frequently used as an alloy in jewelry items, so as long as the piece is large enough, your metal detector should pick it up.
- Ball bearings. Many machines use ball bearings to ensure smooth operation, including cars, turbines, and medical equipment. They are usually made with stainless steel or titanium, so they’ll be difficult for a metal detector to find.
- Pipes. Titanium tubing is used in aerospace hydraulic lines, sports equipment, and bicycles, so you may find a part of one of these larger objects with your metal detector, especially if you’re on the site of an abandoned building.
- Nuts and bolts. Many small construction tools, including nuts and bolts, are made with titanium. Unfortunately, the small size makes it harder for a metal detector to find these objects. However, if you have a high-quality detector and not a cheap one, it’s not impossible.
- Larger tools. Not just nuts and bolts are made out of titanium; larger tools such as hammers and knives are also made of this material. If you were to go to an abandoned construction site, you’re likely to find some titanium objects with your metal detector, despite the material’s non-magnetic properties.
- Pocket knife. It’s more common for pocket knife blades to be made of stainless steel, but there are plenty of titanium blades on the market. Pocket knives are typically relatively easy to discover because they’re easily dropped and a big enough size for most metal detectors to sense them.
You should operate on low frequency for the best chance of finding titanium. Even then, it may be difficult for your metal detector to find this non-magnetic metal.
Brass is a non-ferrous metal with relatively poor electrical conductivity compared to other metals, such as silver. It is not impossible for a metal detector to detect brass, but it is slightly more difficult, and it may require some additional work to calibrate your metal detector for the most success.
Brass contains copper, so many people assume it is highly conductive because copper is the second-most conductive metal after silver. While brass does contain copper, it also has additional materials that lower the overall conductivity, which makes it more difficult for metal detectors to detect.
Luckily, there are some things you can do to increase your chances of discovering brass objects with a metal detector. First, I recommend using all-metal mode. The all-metal mode can annoy users because it leads to lots of signals and time wasted digging up trash. Still, with enough practice, you’ll be able to differentiate amongst the various tones and better understand when to dig and when to keep walking.
Other modes are highly specific and reduce your chance of finding brass objects. For example, using the prospecting mode on a metal detector increases your chances of finding gold but decreases your chances of finding anything else.
I suggest having your sensitivity around 10 kHz if you’re looking for brass. You can have a sensitivity as low as 3 kHz. Still, because brass is already somewhat difficult for a metal detector to find, I recommend having the sensitivity at the higher end so you don’t miss out on anything.
There are many exciting brass items you might be able to find with a metal detector, including the following:
- Shell casings. Brass is the most frequently used material for making rifle shell casings because it can handle high pressures and has a low coefficient of friction. If you’re a shooter, you can save money using a metal detector to collect your brass shell casings and recycle them.
- Plumbing parts. Because brass is so corrosion-resistant and tolerant of extreme temperatures, it is a popular material for plumbing, including pipes, hose bibs, bidets, and sinks. If you’re detecting where a building used to be or an abandoned housing construction site, you might score a piece of this plumbing.
- Musical instruments. Brass instruments make up an entire instrument family, many of which are large, so if one happens to get buried underground at some point, there’s a good chance your metal detector will find it! Brass instruments include the French horn, trumpet, trombone, and tuba. These instruments are recyclable if you find one and don’t want to keep it.
If you find any brass object, not just instruments, that you don’t want to keep, recycled brass has great value, and you can get a decent amount of money if you bring in high-quality brass. Working with recycled brass reduces overall production costs, so manufacturers always look for more. Recycling the material also reduces energy consumption and greenhouse gas emissions.
There are plenty of exciting brass finds that you may encounter with your metal detector. It may not be the easiest metal for a metal detector to find, but it is certainly worth the effort, especially because of its high recycled value.
As with the other metals on this list, a metal detector can detect lead. It happens all the time. However, it is more difficult. Lead is a poor conductor of electricity, so only the best metal detectors can detect it because they can pick up on the small number of frequencies lead sends through the receiver coil.
Another problem with detecting lead is that it usually gives off a high-pitched sound when the detector does sense it. High pitches are difficult for some people, especially hard-of-hearing individuals, to hear, especially when the detector competes with excess noise. For this reason, I highly recommend using a pair of high-quality metal detecting headphones if you want to find lead objects.
I like the Garrett Headphones for Metal Detectors (available on Amazon.com) because you can use them with any metal detector with a quarter-inch (6.35 mm) headphone jack (which is most modern models) and the earpiece padding makes these headphones extremely comfortable to wear. I also appreciate the in-line volume control, which makes it easier to hear audio tones more distinctly.
Possible lead items you could find include:
- Old bullets. Old bullets, especially from the Civil War era, were made of lead, so you may get lucky and discover a piece of history. Be careful, though; it is prohibited to metal detect on historic sites where you’re most likely to find an old bullet.
- Old utensils. Manufacturers did away with lead utensils and cookware because of lead poisoning. Still, before people knew much about the disease, it was common to find various cookware made out of lead. Some of these objects may have made their way into the ground.
- Historical artifacts. In most states, you can’t keep any historical artifacts you find, so if you find something of note made out of lead with your metal detector, be sure to report it to the appropriate authority so you don’t get in trouble. Check out my article on if you can keep things you find with a metal detector.
You’ll probably detect some lead objects with a high-quality tool and lots of patience. However, you should always be careful about spending too much time around lead, especially if you’re touching it.
For a more thorough explanation of how metal detectors are able to pick up lead, I recommend reading my comprehensive guide on detecting lead. In addition to going into more detail about the process, I’ll share a few tips to increase your odds of finding an artifact made of lead: Will a Metal Detector Pick Up Lead? (The Facts Explained)