So is it a myth? Can you demagnetize the little black strip on your credit card just by carrying it around with other cards? The answer is: Yes! You can! In order to understand how this is possible and how to avoid it, here’s a quick scientific breakdown of credit card construction:

The little black strip on the back of your credit card that gets “swiped” when you make a purchase contains tiny bits of magnetized iron that are arranged in a particular binary form. This configuration communicates vital financial information about the card and cardholder through the credit card reader. This information is transmitted to your bank and then back to the vendor instantly to approve (or deny!) the transaction. When your card gets demagnetized, it can no longer transmit this information effectively. The only option is to have a replacement card sent to you, which may cost you if your bank charges a fee for this service.

So What Actually Demagnetizes a Card?

Usually, other magnets. Magnets erase data stored on your card by realigning the iron particles into an unreadable arrangement. So, you should keep your cards away from things with magnets, such as refrigerator magnets and wallets or purses with magnetic closures. Less obvious magnetic sources include those found in speakers and television sets. When in doubt, don’t set your wallet on electronic equipment.

Storing credit cards back to back can also demagnetize them. It is best to place cards in individual pockets of a wallet, rather than allowing them to touch within the same pocket. People used to think that wallets made of eel skin demagnetized credit cards, but eels’ “electricity” doesn’t come from their skin at all. What was actually happening was that the metal fixtures on eel wallets were slightly magnetized, and they were the culprits behind the credit card sabotage.

Other devices well known for their demagnetizing capabilities include pads used to deactivate security devices stuck inside new books, CDs and DVDs (these devices are magnetic, so the pad demagnetizes them and your credit cards), security screening machines, cell phones, magnetic jewelry and strong electrical charges.

Other Culprits

Before you rush out to order a new credit card, you should visually inspect your credit card strip first. Some cards won’t read simply because they are dirty. Try wiping your card back with a damp cloth and letting it dry. Re-swipe your card. If this doesn’t work, inspect the surface of the strip for scratches, which can also render your card unreadable. And remember, if your card is truly demagnetized, a vendor can always hand-punch your account number until you get a replacement card sent to you from your bank.

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