Since 1881 when Alexander Graham Bell invented the first metal detector, its development has been non-stop as more and more uses for it were found.
Today, metal detectors can detect a variety of metals. They are instrumental in different areas like archeology, Civil engineering, Military, Security, food industry, Treasure hunt, and geological research.
From airports to deep in the jungle, metal detectors discover hidden weapons, land mines, knives, buried treasures, and other metallic items but, can they detect lead? The reason for that question is not far-fetched given the distinct properties of lead.
Because of the soft and malleable attributes of lead, many think that it cannot pass as metal. And even if the lead is metal, can it be detected by a metal detector because it conducts electricity poorly? Detecting for lead is quite different from detecting for copper or detecting for cell phones.
You are about to find out if metal detectors can actually detect lead. Read through!
How does a metal detector work?
Using a metal detector is not complex. Once you turn on the machine and have configured it to your preference, direct the head towards the area you wish to check. The search coil in metal detectors transmits electromagnetic field into the ground. Metal objects within the waves send electromagnetic fields that the detector’s transmitter catches.
When that happens, the metal detector receives the response and alerts the user on the types of metal found.
Some detectors can tell the difference between metals. That means they can be configured to search for specific metal types and leave the ones that do not fall into the set category.
Metal detectors can use VLF, PI, or BFO technology to find metal objects. Of all the three types of metal detector technology, BFO is the easiest to operate while VLF is the most common. PI metal detectors are the least used among the three technology types.
How metal detectors work based on their technology.
How a metal detector works depends on the way it is wired. Check out how they work using the VLF, PI, and BFO technology;
- VLF (Very Low Frequency): A VLF detector has two different search coils- transmitter and receiver coils. The transmitter coil sends an electromagnetic field in the direction it is pointed while the receiver locates signals from metal objects in the ground and triggers the control. The detector estimates the depth of the buried metal through the frequency it sends out. If the object is close to the surface, the frequency will be strong and if it’s deep down, the magnetic field is weak.
- PI (Pulse Induction): This type of technology is not as common as the VLF. PI metal detectors use Pulse Induction to find metals. They may have one to three in them, unlike the VLF. The system works by sending pulses of current that transmit electromagnetic field briefly. The pulses can be up to a hundred per second. As each pulse fades, there is an electrical spike that doesn’t last for more than microseconds. It then sends reflected pulses that last for less than a second.
When the PI detector is near a metal object, the reflected pulses last a little longer than they would do if a metallic item was not nearby. When that happens, the detector makes a sound to show that a metal item is within the area being searched.
- BFO (Beat-frequency oscillator): The BFO detector has two coils of wire with one present in the search head and the other in the control box. An oscillator that transmits pulses is connected to each coil. When the pulses come through the coils, they generate radio waves.
If there is a metal object nearby, it sends an electromagnetic field that affects the radio waves. Based on the signal transmitted by the coils, the detector makes beat sounds to tell that a metal object is within the area.
Does lead show on a metal detector?
Since metal detectors are designed to check for metal within an area, any metallic objects will trigger a signal within it. Lead may be a poor conductor of electricity and denser than other metal elements, but they still count as metal.
If your metal detector cannot detect lead, you may be using an old model detector. One of the common properties of lead is its low conductivity.
Most old model metal detectors cannot find metal objects with low conductivity. Once the lead is too far from the machine, it will not transmit any signal and thus remain unfound.
Another reason why your detector cannot find lead is if it has been configured that way. Some machines that detect metal can be set to ignore some kind of metal.
Once yours is configured to leave out lead, it will not send a signal if any appears.
Best place to go metal detecting for lead
The best place to go metal detecting for lead is in the woods. Typically lead is found around old industrial sites. This is because lead was more commonly used in manufacturing and production in the past compared to today.
It is highly advised that you do not search for lead unless you have appropriate safety training. Lead is a dangerous material a can be harmful if you are exposed to high amounts.
Typically people only go metal detecting for lead if you are involved in industrial constructions or project management.
What metals cannot be detected by metal detectors?
Some metals have low or no electrical conductivity. That makes it tough for metal detectors to find them. A metal object that conducts electricity poorly cannot be found since its signal cannot be detected.
The only way such an object can trigger a metal detector is if it is close. Sometimes, even a close-by metal with low electric conductivity may not be seen if it is small.
One of such metals that may be difficult for metal detectors is stainless steel. It conducts electricity poorly and may not be found unless it is close. Stainless steel sends weak electromagnetic signals that cannot be picked by most metal detectors.
Some of the elements that a metal detector cannot detect are;
The distinct properties that lead have do not make it less of a metal. Lead can be detected by metal detectors if its signal can be found. If your metal detector cannot find lead, it may be because the machine is programmed to work like that or the lead is too far away.
Julie comes from a long line of metal detectors. Her family has been in the hobby for over 45 years and has recovered large amounts of civil war artifacts as well as a fair number of bottle caps. Lately she has been focusing on metal detecting in the Rocky Mountains.