Speakers, some cell phones, and magnetic clasps on wallets and purses can also demagnetize a credit card, and cards such as transit passes used on many subway systems are even more susceptible to this problem.
If you find the magnetic stripe on your credit card is no longer working, it may have become demagnetized.
Phones do create a magnetic field, but thankfully, it isn't strong enough to demagnetize credit or debit cards. The small magnet in the phone's speaker is the main culprit of generatingthe magnetic field. This field, however, is too weak to cause sufficient damage to a credit card magnetic strip, with some exceptions.
Destroy the Magnetic Strips and Chips on Your Cards
It's not enough to swipe it back and forth once or twice. Exposure time is what demagnetizes the strip versus magnet strength, so even a refrigerator magnet will do the trick if you rub it back and forth for a few minutes.
When one magnet comes close to another, it affects the other card's magnetic field. With a mag stripe card, this same principle applies when it comes into contact with other magnetized objects (like credit and debit cards, key chains, etc...) and thus results in the card being demagnetized and the data erased.
An RFID-blocking wallet uses a layer of carbon fiber or aluminum to block the electromagnetic signal emitted from your card. The wallet acts like a Faraday cage. It creates a barrier and cancels out electromagnetic signals. Whether you've owned a contactless payment card or not, the market for it has grown rapidly.
A credit or debit card can also get demagnetized if the strip gets extremely scratched. Try storing your card in a safe place, like a wallet (away from the clasp or other metal parts, of course). It's best to store your card in a soft, cushioned place away from spare change or other rough objects.
You may have heard that a magnet can 'demagnetize' a credit card's magstripe. This is not generally true. The magnetic stripe on a credit card is made from a ferromagnetic material—that is, a material that independently retains its magnetic properties.
Rest assured, your EMV chip card will withstand magnetic meddling.
Most cards are magnetic strip swipe cards, and can become demagnetized. The most common reason for a room key to get demagnetized is the use of cell phones. I have seen many a guest carrying their cards in the same hand as their cell phones. Receive a call and it will be demagnetized.
As the Wireless Charging Pad uses an electromagnetic field, it is possible for this to damage any bank cards or any other magnetic cards. If you are using a wallet case with a magnetic card inside the case, please ensure that any magnetic cards have been removed from the case to avoid any damage to your magnetic cards.
Your card's chip or strip gets a little dirtier with every surface it encounters; eventually the buildup of grime may mean your credit card can't be read by the payment terminal. If after wiping your card down it still won't work, it may be a good idea to reach out to your card issuer to get a replacement card.
Although banks claim that RFID chips on cards are encrypted to protect information, it's been proven that scanners—either homemade or easily bought—can swipe the cardholder's name and number. (A cell-phone-sized RFID reader powered at 30 dBm (decibels per milliwatt) can pick up card information from 10 feet away.
Storing cards back-to-back – Credit cards are slightly magnetized. If you store them next to each other, the magnetization of each card can damage the other cards they're stored with.
The MagSafe iPhone wallet won't demagnetize your credit cards, so you can stop freaking out now. You'll just want to be careful with hotel keys and gift cards. On Tuesday, Apple announced it was implementing its MagSafe technology into its new smartphones.
The magnetic strip on credit cards come in two varieties. The high-coercivity ones, like a typical credit card, require a field strength of somewhere around 4,000 gauss to demagnetize. The low-coercivity ones that are often re-written, like hotel keys or gift cards, require about 300 gauss.
They also need to be much closer to scanners to be read. So, skimming theft risk is much lower again. RFID sleeves and wallets still block any signals from these cards. So, in the unlikely event someone gets so close they can read your card, you'll still have protection.
The materials used in RFID wallets, such as aluminum or copper, protect against the radio waves used in contactless payments. This shield does not affect the magnetic strip or chip in the credit card, and it does not cause any damage or harm to the card.
Myth two: credit cards demagnetizing hotel key cards
Can a HiCo card, such as a credit card, demagnetize a LoCo hotel key card? Both Cunningham and Hermanson say no. Despite what you may hear in the hotel lobby, it is not unsafe to store two cards with their mag stripes facing each other.
Those stripes can occasionally get demagnetized by other things that you routinely carry in your pockets or purse. Some gift cards include a scratch-off panel. If you're too zealous or use something too sharp you can accidently remove the numbers underneath, says Mendelsohn.
Currently, some ATMs use the mag stripe to identify that a card has been correctly inserted (to open the gate to ingest the card), but they do not read the data off the stripe - ATM dependence on the presence of the stripe is one of the few reasons it's still included on new cards - that and fuel pumps anyway.
The aluminum will disrupt most electronic signals. You can also wrap each credit card in aluminum foil and place the wrapped cards in your wallet. The foil shields the card from scanners.
Use an RFID blocking wallet
Even if you are aware of where your wallet is, criminals can still easily scan your contactless cards. Luckily, there are wallets available which block the radio waves between a card reader and the RFID chip in your card, so data can't be read no matter how close in proximity.