Plastic Bags Improve Credit Card Swiping

what is happening is there is some smearing of small magnetic particles along the magnetic stripe.

So as you run the card through these out of place particles create a signal, often where there is a local zero in the mag field, so the data stream gets corrupted. Since it is check summer, one bad bit = failed read.

Now the particles are small, so if you increase the gap for a few thousandths of an inch the field from these partciles dropps off due to square law losses faster than the far larger magnetic stripe zones, which tend to drop in a more linear manner.

This impsoves the signal to noise ration and the system kicks out the far lower noise and does not read it.

It is the beginning of the end for the card. As times goes by it will get worse.

One way to prevent this is to use a thin layer of tape on all your cards from new, and replace it as it gets grated off.

thanks aurizon beutifully put and very informative

Thanks, I really should proof read and cull the typos before I finalize a posting, and now the edit window has closed and they will stay there forever.

Thanks - this was very informative. It's catching on at supermarkets all over the country.

Thanks, I was wondering about this since it happened to me twice this weekend.

Is there an English translation?

The magnetic stripe is made of fine particles of a magnetisable oxide embedded in a plastic binder. It is put on and then a series of magnetic highs and lows and placed on the strip from an external writer.

You then use it.

In time the plastic layer wears down and small bits of oxide and their magnetic code get scraped of and either removed or repositioned further along by a smearing action.

So now when you read the card there are magnetic bits in the wrong position = different code. Since this is a secure checksummed code, the check sum fails and you get nothing read at all.

Since the bulk of the magnetic stripe is intact and only small particles have been moved, these small particles have a small field and if you can remove them a small distance from the reading head they(being small) will not be read and the large original signature of the full stripe will be read. The easiest way to do this is a small plastic bag or a strip of scotch tape along the stripe. The give you a small spacing.

In any event once you have enough wear to need this, it is near the end...go to the bank and get a new card made.

http://www.newscientist.com/article/mg19225752.500-money-bags.html

As Requested: The English translation Credit Cards have data in the little stripe on the back -- you knew this. As the stripe wears, the data sometimes gets a little corrupted and has little pieces of bad data. This happens from it getting rubbed in card readers for years. The plastic bag helps because it makes the bad data harder to read, then the good data. It literally covers the bad information up, while the good data is strong enough to be read through the plastic bag.

Lamen english translation: Plastic bag makes it work because of things like 'stuff'.

It may be the card's strip, but the reader is an issue/factor as well. My card has worked great for a year on all the readers except one at a store I frequent often. The only solution at that one store is to use the plastic bag trick.

What could be the problem with the reader?