Does Aluminum Set Off Metal Detectors?

Answer

Yes, aluminum does set off metal detectors.  

Short Explanation

Contrary to rumor, aluminum will set off metal detectors and will not shield x-rays or radio waves. This misconception seems to come about due to how metal detectors work and the properties of aluminum.  Aluminum is nonmagnetic but metal detectors do not detect magnetic items. Metal detectors detect electrical conductivity and all metals are conducive to some extent.  

Glod, silver, copper, tin, and lead are also nonmagnetic and all of these metals can be detected by a metal detector. There is so much aluminum in the ground, it makes up 8% or the crust as well as all the aluminum trash, most detectors have a setting to screen it out.

If aluminum could not be detected by metal detectors, all security metal detectors at the airport, concerts and other locations would be completely ineffective.

Find the right detector, then find your treasure!

Table of Contents

Longer Explanation

Types of Metal

There are two major types of metal in nature, ferrous and nonferrous.

A ferrous metal contains iron and is magnetic. Ferrous metals such as carbon steel, alloy steel, stainless steel, cast iron, and wrought iron are prized for their strength and durability.  Ferrous metals are prone to rust because of the carbon, except for stainless steel.

 A nonferrous metal does not contain iron and is nonmagnetic.  These metals include copper, gold, silver, tin, lead, and aluminum.  These metals are lightweight and much more malleable than ferrous metals. The non-magnetic properties of nonferrous metals make them perfect for wiring and electronic applications.

 How Metal Detectors Work

Metal detectors do not work on magnetism, rather electrical conductivity.  Metal detectors do send magnetic pulses into the ground but they are not looking for magnetic items.  Without going too deep into the science, the magnetic pulses from the metal detector’s transmitter induce, or create, an electrical current in any metal objects in the ground. This induced electrical current will then create a magnetic field around the object, even if the metal itself is nonmagnetic.  Electromagnets and electricity generators are based on this principle developed by legendary scientist James Clerk Maxwell.

Metal detectors also have a receiver coil which is usually wrapped in metal wire.  When this wire wrapped coil passes over the magnetic field created by the transmitter another electrical current is created.  The current created in the receiver coil is sent to a loudspeaker or other sensor and reveals metal in the ground. The larger or closer the metal object in the ground is, the stronger the induced magnetic field will be, creating more electrical current in the receiver and a louder or stronger signal on the metal detector.

  1.     Metal detectors send magnetic pulses into the ground.
  2.     These metal pulses induce electrical currents in metal in the ground.
  3.     The induced electrical currents create magnetic fields around the metal objects.
  4.     These newly created magnetic fields induce electrical currents in the receiver coil of the metal detector.
  5.     The induced currents in the receiver flow to a loudspeaker or sensor on the metal detector.

To summarize: Electricity creates magnetism, which creates electricity, which creates magnetism, which creates electricity then causes a beep.

Simple!

How to Find Aluminum with a Metal Detector

The best bet is to consult the owner’s manual for the detector to learn about which settings work best with which metals.  Manufactures might have proprietary technology or use different terminology for the settings on their machines.  

It is also helpful to test drive a metal detector by burying different types of metal and checking how the unit responds.  A nail, a coin, a ball of aluminum foil all produce different readings. Be sure to mark the location of any valuable items, like gold and silver, used as test objects in case something goes wrong or the detector malfunctions.

Aluminum has value but is not as valuable as other metals. If the detector is picking up too much aluminum, try screening out the signals using discrimination or other features on the unit.

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Conclusion

Since metal detectors work on principals of electric conductivity rather than magnetism, nonmagnetic materials such as aluminum can be detected.  Be sure to read the owner’s manual to best understand how to detect or ignore aluminum in the ground.

Find the right detector, then find your treasure!

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