On 12/19/2013 9:37 AM, dpb wrote:
On 12/19/2013 7:46 AM, Norminn wrote:
Card doesn't work when "swiped" through the machine unless one covers it
with plastic....one cashier suggested putting plastic grocery sack
around the card and then swipe it, and it worked. Any idea why this
works? (We've requested a replacement card).

It's a fairly common thing clerks learn pretty quickly.

I've not researched it but my supposition is that there's noise in the
signal owing to the deteriorated portions and the plastic reduces these
lower-level confusing inputs to the point the reader can then reproduce
the real data. IOW, it (the plastic) improves S:N ratio more than it
reduces S.

Over the years I've had several that get to where it's needed before
they reach the point of automagic renewal. It's also clear some readers
are better than others--either they also age or they're just higher
quality, I know not which.

--


That sounded very logical, so I decided to Google it....I had been
thinking it might be a local practice, but apparently not...here is a link:

http://blogs.howstuffworks.com/2009/...a-credit-card/