From credit cards, EC cards and hotel key cards to membership cards, there are many cards whose key data is stored on a magnetic strip. If this magnetic strip is damaged, the computer can no longer recognise the card and has no access to the information. How do magnetic strips get damaged?

 

 

The magnetic strip contains countless microscopic, magnetised iron particles that are arranged in a specific pattern. When the respective computer scans the magnetic strip, it translates the read pattern and receives the corresponding information. If the iron particles on the magnetic strip are demagnetised, the pattern is broken and the computer can no longer recognise it.

 

When a credit card is swiped, for example, the computer recognises the pattern of particles, which is unique to each card, and sends a signal to the database. From there, the information is sent to the corresponding house bank, which has access to the account data. 

If the pattern of the iron particles is altered, i.e. by damage or demagnetisation, the computer cannot decipher the information and the card cannot be read.

 

Magnets can disrupt the pattern of the iron particles. The stronger the magnet, the more likely it is that the magnetic strip will be demagnetised. Even weaker magnets, such as the magnetic clasp of a handbag or wallet, can damage the magnetic strips if they are in contact with them over a longer period of time. 

 

 

You only need to worry about strong magnets, where a brief contact can cause damage. Normally, it is unlikely that shutter magnets will remain in contact with the magnetic strip long enough to demagnetise it. It is only important that you do not store two cards with magnetic strips directly strip on strip in your wallet, because after a while the two magnets may well interfere with each other.

 

Much more frequently than demagnetisation, a scratch is the reason why a card is no longer readable. When removing and inserting the card or storing it with keys, it can happen that the magnetic strip breaks through the pattern of iron particles and the computer cannot interpret the information.