OT, but an interesting technical tidbit

[jmbjmb]

Here's one explanation.

 

http://www.creditcards.com/credit-card-news/lick-plastic-bag-credit-card-secrets-1273.php

 

[rrinker]

 I have 2 theories. One is the extra thickness of the plastic bag actually gets a more steady contact between the card and reader - it's magnetic so it doesn't need physical contact, the palstic does nothign to alter the magnetic field. On the opposite side as the reader head is just a mechanism to push the card tight agaist the reader, if the spring is weak or worn the thickness of the bag may be enough to get actually a closer contact.

 Theory 2 is that the reader head is dirty, since it IS in physical contact, it's going to scrape a small amount of the magnetic media off every card that gets slid through. And pick up any dirt that may be on someone's card. The plastic may serve as a 'head cleaner' of sorts and clean off the reader head and allow it to work.

                                                  --Randy 

[mozetti]

 My vote is for a static charge buildup that allows the information to be transferred from the magnetic strip to the reader. Having no knowledge or experience in this field, I'm pulling this completely out of my a ... caboose. But it sounds like it would work.

[Vail and Southwestern RR]

I don't think it "should" work, but I've seen it enough times that I have a hard time not believing it!

Some places won't take a card that won't read.  In the age of counterfit cards, and with an additional cost to them, I guess I can see that, too.

[maxman]

duckdogger

 From the card reader's perspective its the same as putting a bag over an ugly woman's head.

Ouch.  So I suppose that "double-bagger" is the term used when you need to put two bags on an ugly credit card in case the first bag breaks?

[duckdogger]

 From the card reader's perspective its the same as putting a bag over an ugly woman's head.

[tbdanny]

Could be some sort of electrostatic 'filtering' effect from the bag - same thing that makes them hard to open and cling to your hand.

[1948PRR]

Don't know if this applies to magntics, but laser bar code readers can be too "hot".

Maybe the bag acts to reduce the power in some way.

[RF&Prr]

IMO, I vote for the decreased read errors by placing it in the bag.

http://www.popsci.com/node/16903

[Phoebe Vet]

I have never worked in a supermarket, but I did own a business that took credit cards, admittedly not at the volume of a market, and typing the numbers in is neither difficult nor particularly time consuming.  Accuracy is only a minor issue because if you type it wrong it will fail the check sum.  There is no chance of charging the wrong card number.

Now... Who do you suppose discovered that the bag trick worked?

[river_eagle]

and the card company charges the merchant a higher fee for a manually entered transaction, as much as an extra 1% .

[tbdanny]

Phoebe Vet,

Having worked in a supermarket for 3 years, I can say that manually typing in the numbers would be slower.  The checkout software (NCE, I think) required either another 'screen' of the program to be activated, or for a swipe to fail 3 times in a row.  Then there's the time taken to type in 16 digits and the expiry date, and the possibility of human error that has now entered the situation.  The plastic bag over the card trick saves time and removes the chance of error.

Cheers,

tbdanny

[Phoebe Vet]

Wouldn't it have been easier for her to just take the card and type the numbers in on the cash register?

 

[novicerr]

 I can't tell you why it works, but I have seen it done before. Can't remember which store I was in tho. Wasn't very long ago either.

[MisterBeasley]

I was at the supermarket earlier today.  The woman in front of me swiped her credit card, and the reader gave her an error.  I wasn't surprised, because the card had a good 1-inch chunk missing from the corner, including part of the magnetic strip.  She pulled out a second intact card, though, and that one had the same problem.

The woman running the checkout took the broken card and put it into one of those thin plastic grocery bags.  She smoothed it so the magnetic strip was on the edge, and ran the card through the reader.  It took.

When it was my turn, I tried to swipe my card, which has no cracks, and which always works in machines.  No go.  So, I tried the trick with the bag and it worked.  Now, obviously there is something wrong with this card reader, perhaps exacerbated by the very dry air in this cold snap, but why would putting a bag over a credit card make it work?

I know it has nothing to do with trains, but this DCC forum is full of people who would enjoy this one.