In most cases if the underwire of the bra is small and thin, it can go through the metal detector, like how zippers on pants can go through. If the bra size is larger, and the underwire is thicker and larger, then it has a higher chance of setting off the metal detector.
This threshold varies from detector to detector and is adjustable by the operators. An underwire bra has about as much metal as a pair of jeans (zipper or button & rivets on the pockets). At airports, they try to keep them adjusted so people going through wearing jeans will not set them off.
No. Its not enough to trigger a metal detector. Considering such small metals are found everywhere from bags to jeans it would be headache if the alarm went on at every turn I suppose the security people do consider such trivial things before setting up a metal detector.
Underwire construction
The underwire can be made of metal or molded plastic; most are metallic. Plastic underwire has a very small share of the market because it does not provide the same support and rigidity offered by metal underwire.
In underwire bras, a sturdy metal wire sits beneath your bustline to lift and support your breasts.
One of the major benefits of underwired bras is support, especially if you have a larger chest. With the support of a wire, you can experience less back pain or strain that you might normally feel throughout the day. Additionally, underwired bras provide better lift, separation, and shape of your breasts.
Anything Metal
Metal jewelry and piercings can set off the metal detector. Likewise, belt buckles can easily cause issues, and most TSA rules and regulations require you to remove them anyway.
For women, if possible, do not wear an underwire bra (the metal can throw off the magnetic field). Sports bras are usually good and we have hospital gowns to change into if necessary.
Airport body scanners alert the TSO to threats—mainly weapons such as knives, guns and explosives. They are designed to detect “metallic and nonmetallic threat items,” according to the TSA. Those are things like explosives or knives made out of materials other than metal, like ceramics, says Malvini Redden.
Underwire bras (or wired bras) have sturdy metal or plastic wire beneath the cup of each breast. This wire is usually sewn into the bra with extra fabric around it so that it feels more comfortable. The goal of underwire bras is to lift your breasts away from the wall of your chest and give each breast a defined shape.
"Some airport scanners are sensitive to the metal underwire components in more traditionally-made supportive bras – so you might want to swap them out for a softer wireless alternative such as a T-shirt bra or bralette." Plenty of people have experienced problems while wearing underwire bras at airports.
Everyday examples of items with nickel are coins, earrings, watches, belt buckles, underwires and fastenings of bras, the rivets on your jeans and the eyelets on your shoes. Less obvious is the nickel "hidden" in powder eyeshadows and the applicators or wands of mascara and there are foods that contain nickel too.
Metal detectors can detect both ferrous and non-ferrous metal types, although they detect ferrous metals more easily due to their magnetic properties. Ferrous metal contains iron and is often magnetic, while non-ferrous metal consists of other elements like nickel, aluminum, and zinc.
Electrically conductive minerals, soil minerals, and iron underground pipes can also interfere with a metal detectors' signal.
Please wear clothing without metal buttons or zips down the centre of the back. If applicable, please do not wear a bra with metal fastenings. Skirts, tracksuit bottoms and shirts can all be left on during the X-ray.
Depending on which part of your body is being scanned, you may need to wear a hospital gown during the procedure. If you don't need to wear a gown, you should wear clothes without metal zips, fasteners, buttons, underwire (bras), belts or buckles.
As discussed in the prior Q&A, objects made of ferromagnetic materials — iron, cobalt, manganese, nickel and a few rare earth elements and their alloys — have the potential to move or twist in a static magnetic field creating potential danger.
It's best to avoid socks or shoes that are tight around the ankles. Sitting still on long flights slightly increases your risk of deep vein thrombosis – which is when the blood clots in deep veins – especially in your legs.
TSA Guidelines for Jewelry
In general, small pieces of jewelry like rings and earrings can be worn through TSA checkpoints without issue. However, heavy jewelry with bulky metal components or multiple pieces can trigger the scanner.
Airport scanners can see detailed images of your luggage contents such as metallic and non metallic objects, but also organic materials. How does it work? Even though the technology behind scanners it is very complex, the process of scanning your body and suitcase is quite simple.
Bras that have an underwire are extremely supportive, especially for fuller busts. This is because the wire enforces the band which is the part of the bra that gives the most support. It's easier to achieve separation between the breasts with an underwire.
Wearing an underwire bra every day can provide support and shaping for your bust. It's important to take breaks from wearing underwire bras to give your skin and tissues a chance to rest. Prolonged wear of underwire bras can lead to discomfort, skin irritation, and pressure on breast tissue and lymph nodes.
However, if you find the compression to be comforting, you might still choose to do so. If that's the case Sekhon says to look for a soft, flexible bra without underwire. “Sleeping in a tight bra that applies pressure on the skin can cause disruption to sleep and breast/skin irritation,” she explains.