The simple answer is: sometimes, but not reliably. Aluminum is a metal, but its conductivity is significantly lower than that of ferrous metals (like iron and steel) or even non-ferrous metals like copper and silver. This difference in conductivity is the key factor in determining whether a metal detector will detect aluminum.
Many metal detectors, particularly those designed for hobbyist treasure hunting, are primarily tuned to detect ferrous metals. These detectors may ignore or produce a very weak signal when encountering aluminum. The size and shape of the aluminum object also play a crucial role. A large, thick piece of aluminum will have a better chance of being detected than a thin, small piece.
How Metal Detectors Work & Why Aluminum is Tricky
Metal detectors operate by emitting an electromagnetic field. When this field encounters a conductive metal object, it induces eddy currents in the object. These currents, in turn, create a secondary magnetic field that the detector's receiver coil picks up. The strength of the signal is directly related to the conductivity of the metal. Since aluminum's conductivity is relatively low, the induced eddy currents are weaker, resulting in a fainter signal or no signal at all.
What Factors Influence Detection?
Several factors influence whether a metal detector will detect aluminum:
1. Type of Metal Detector:
- Pulse Induction (PI) Detectors: These are generally more sensitive to all metals, including aluminum, compared to VLF detectors. They're often preferred for detecting gold and other less conductive metals, so they’re more likely to pick up aluminum.
- Very Low Frequency (VLF) Detectors: These are common and more affordable. They're often less sensitive to aluminum and may only detect larger or thicker pieces. Many VLF detectors have settings that allow you to adjust sensitivity and discrimination, potentially helping detect aluminum.
2. Size and Thickness of the Aluminum Object:
Larger and thicker pieces of aluminum produce stronger eddy currents, increasing the likelihood of detection. A thin aluminum can, for example, might be missed entirely, while a large aluminum pot could produce a detectable signal.
3. Ground Conditions:
Highly mineralized soil can interfere with the detector's ability to pick up weak signals, making aluminum detection even more difficult.
4. Detector Settings:
Many metal detectors allow you to adjust the sensitivity and discrimination settings. Increasing the sensitivity increases the chance of detecting aluminum, but it also increases the likelihood of false signals from other metals or ground minerals. Discrimination settings allow you to filter out certain types of metals, but improperly setting this could cause the detector to ignore aluminum.
Will a Metal Detector Detect Aluminum Foil?
This is a frequent question. The answer is generally no. Aluminum foil is very thin and therefore has extremely low conductivity, making it almost impossible to detect with most metal detectors.
What about Aluminum Cans?
Aluminum cans are a little more complex. While they are thicker than foil, they are still relatively thin and may not always produce a strong enough signal to be detected. The size and the detector's settings will determine whether it will register a signal.
Conclusion
While a metal detector can sometimes detect aluminum, it's not guaranteed. The likelihood of detection depends on the type of metal detector, the size and thickness of the aluminum object, ground conditions, and the detector's settings. If you're specifically looking for aluminum, a pulse induction metal detector with high sensitivity is your best bet. However, even with the best equipment, smaller or thinner aluminum objects may remain undetected.
