Why Do Credit Cards Get Demagnetized?

Basically, the reason credit cards become demagnetized has to do with electrons and magnets. Of course, the complete answer to this question is much more complex than that. This wasn’t a problem in the past when a credit card’s raised numbers (on the front of the card) were imprinted on paper when a credit-card machine passed over the card.

While there are still raised numbers on the cards, information about the card is gathered when the magnetic strip on the back is read by an electronic card reader. Think of the basic magnet and iron filings or small iron nails when you want to understand how this process works. The strip on the back of a credit card has microscopic pieces of iron in it. These are arranged in a particular pattern when the card is activated, similar to the way iron filings move into a line or other pattern when a magnet comes near them.

The small iron particles are protected by a very thin film. Magnetizing them orients them in a particular direction. At least three separate tracks are read on the strip, with each track containing certain characters or numbers that have meaning to the computer gathering the information.

If some magnetic source comes close to or into contact with the strip, the iron particles are demagnetized. The machine can’t read the pattern as it should. The card number and other information can’t be gathered by the computer/storage device.

Credit cards can become demagnetized in a number of ways. Some of the materials in wallets and purses may be responsible for this. Friction might cause enough of an electrical impulse to realign the iron particles, demagnetizing the strip. Some wallets and billfolds were held closed with a small magnet. This sometimes generated enough of an impulse to demagnetize the card. If the leather or other material was thin enough or if the card was stored close enough to the clasp, there could be a problem.

Some of the more obvious ways to demagnetize a credit card strip would be to get the card too close to other magnets, such as those design magnets on the refrigerator. It’s possible that some scanning stations used in airports and government buildings might demagnetize the cards too. Electronic sound equipment is often constructed with magnets as a necessary part. These could cause the problem in rare cases.

Some travelers have reported problems with credit cards and electronic room keys in hotels and motels as well. Storing credit cards and key cards back to back may erase or realign the information stored by the iron particles. The credit card may be unreadable when you use it the next time, or the key card may not unlock the door to your room when you try it after it has been stored in contact with another card.

While magnetized credit cards making buying more efficient in most cases, getting the cards too close to a magnet or strong electrical field might cause problems.