This could be either a factual or ancedotal answer so I wasn’t sure where to put it, but was with my niece’s kids at the local amusment park and we passed a stereotypical “Goth” teenage couple with maybe a dozen face, nose, and ear piercings each, and the full assortment of metal necklaces, bracelets, and metal chains. One of my niece’s kids piped up “I bet they set off the metal detector on the way in”
So that actually begged the question. Do metal detectors pick up the aggregate amount of metal a person has, or is it more a variable of the amount of metal in a specific place on a person, say a single big knife as opposed to a dozen body piercings? Is there maybe a different type of metal used in jewelry as opposed to weapons that metal detectors are more sensitive too? Anyone seen a metal detector alert to jewelry? Are metal detectors able to be tuned to how many false negatives are acceptable in order to minimize false positives?
At the amusement park you’re specifically told to carry phones, watches, and keys through the detector but that they will alert on metal sunscreen containers. I did have a cheap metal clip-on type watch that set them off, but that’s the only thing I’ve had an issue with personally, my keys and iPhone 13 Pro go through fine.
I’ve seen in China someone setting off an alarm at a historical site. It was a foreigner (well at least a White person) who indeed was wanted and the alarm was going off in her lower abdomen. She was taken by the security folks to a private area. I didn’t see what happened after that.
I have been to a courthouse several times since then, and I’ve seen people with big hoop earrings go through.
I wear three rings and they have never set off an airport metal detector, nor have I been requested to take them off. I have been told to take a pen out of my shirt pocket, however.
Do metal detectors detect all metals or only Ferromagnetic ones? I have a plate of some inert metal in my ankle and it has not set off metal detectors at airports.
The only anecdote I have is: I saw a young man at SFO with a studded jacket, bullet belt, chains, piercings everywhere, etc., and he was going back and forth through the metal detector for a good long while. They were still at it after ten minutes when I got through the other gate.
I don’t know what they use at the airport, but I figure it should be able to detect conductive materials?
Certainly they can tune for what it is they are looking for.
My father had metal pins in both of his thighs from injuries he had suffered decades ago. He used to have to inform the security staff that they would set of the metal detectors. I think he travelled with some proof of it but still got secondary checked every time.
Any conductive material should work, as you can induce a current (and hence a magnetic response) in any conductor. How effective it is, though, depends on how big of a loop you can form in the conductor. A wire hoop will show up much more strongly than the same amount of metal is a spherical lump.
Of course, most detectors also have adjustable sensitivities. You probably could, in principle, make a detector sensitive enough to register ordinary rings and the like; you just wouldn’t want to, because it’d ping on almost everyone.
I’ve spent the last almost six years wondering if the titanium rod installed in my husband’s leg after a fracture would cause trouble. I don’t think he’s had to pass through a security checkpoint that uses metal detectors in that time, so we still don’t have any actual experience with that.
Here’s another anecdote: the first time I went through a metal detector at airport security after I got a cardiac stent, the alarm went off. I was puzzled at first, but then remembered the stent and pointed it out to the guard. He checked with a handheld device and let me pass.
I know, that’s why I was so flabbergasted. It also never happened again, maybe the detectors at Fuerteventura airport where it happened are extra sensitive.
I was in Alice Springs many years ago. there was a Galxy C5-A on the tarmac, and the guy behind me was in the USAF overalls. He was setting off the detector as I left security. Those overalls are basically dozens of metal zippers with a bit of fabric in between.
The walk-through metal detector I have used for scanning visitors at a juvenile detention center had settings that supposedly made it less sensitive to precious metals. On the various treasure hunting TV shows, their metal detectors make different sounds which the users claim can distinguish between precious metals and iron.
Due to rebar in the concrete floor beneath a walk-through detector, sometimes the lowest detector elements need to be disabled to prevent the floor from setting off the detector. (We had to do that with ours.) Those detectors might then have difficulty finding metal in your ankle or concealed in the sole of your shoe.
Mrs. Martian’s knee replacements (titanium and plastic) always set off metal detectors. At the airport she doesn’t even try, just heads right to the alternate Bullwinkle scanner.
That’s what it’s called? I was trying to think of the name, why Bullwinkle? I always have to do that, titanium hip. It almost always says I have something around my neck, besides my gold wedding band I don’t have anything but the hip and a zipper.
That probably explains a pattern I noticed a few years ago at Stansted airport. Most of the detectors would pick up the cobblers nails in my shoes, while some others wouldn’t. It was always the same detectors that let me through so I’m now guessing they were the ones nearer to rebar or other structural metal.
We worked a NSSE (National Special Security Event). There was a row of (temporary) metal detectors setup at each of the multiple entrances. I’ll never forget the woman on that team working to dial them in. She was wearing shorts & had a big knife strapped to her calf. She’d repeatedly go thru a given metal detector until they had it dialed in just right, then move to the one next to it & repeat on that one before moving on again.