What will block damage to mag stripes?

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Discussion Overview

The discussion centers around the protection of magnetic stripe cards from damage, particularly in relation to potential causes such as proximity to cell phones and magnetic closures. Participants explore materials that could shield these cards from magnetic fields and discuss the effects of heat on card functionality.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes an increase in "demagnetized" cards and seeks lightweight, durable materials to block damaging magnetic fields from cell phones and magnets.
  • Another suggests using Mu metal, which is known for its high permeability, as a protective material for cards, stating it won't affect cell phone functionality unless it covers the antenna.
  • A participant references a Myth Busters episode that tested the effects of cell phones and magnets on credit cards, concluding that these devices do not produce strong enough magnetic fields to cause damage.
  • One participant expresses concern that heat may damage cards, sharing personal experience of cards malfunctioning after being left in a hot car.
  • There is a clarification about the correct term "Mu metal," with a humorous note about the confusion with "NU metal," which is a music genre.
  • A later reply mentions a technique of enclosing a card in a plastic bag to improve reading success, speculating that it may involve contact electrification or electrostatics.

Areas of Agreement / Disagreement

Participants express differing views on the causes of card damage, with some attributing it to magnetic fields and others to heat. There is no consensus on the effectiveness of proposed protective materials or methods.

Contextual Notes

Participants discuss various assumptions about the strength of magnetic fields from everyday devices and the effects of environmental conditions on card functionality, which remain unresolved.

Who May Find This Useful

Individuals interested in the durability of magnetic stripe cards, those seeking protective solutions for such cards, and readers curious about the effects of environmental factors on card functionality.

thecat
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Seems like an epidemic lately of "demagnetized" credit cards, transit cards, etc. - apparently due to the card's proximity to cell phones and/or those magnetic closures on briefcases and purses...

If I were to attempt to protect my cards from any such damage, what material could I use which would also be reasonably lightweight and durable?

(in other words, what blocks the mag-stripe-altering magnetic field frequency generated by low-power simple magnets or by cell phones? - and a related question is whether this material would also cause any communication issues for the cell phone)

Any ideas are appreciated.
Thank you,
TheCat
 
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Goggle for NU metal. It can be had in thin sheets. Cut it to a suitable size, fold it in half and put the cards inside. You'll have to do something about the sharp edges and corners. It won't affect a cell phone unless you cover the antenna if that's the question.
 
There was recently an episode of the show 'Myth Busters' that aired sometime this month in Australia on this very topic (For those that have never seen this show, it basically consists of two guys that go around scientifically testing urban myths).

These guys put several credit cards under all kinds of grief from cellphones, money clips etc, and the credit cards still worked without a hitch. These guys even got a decent sized electromagnet and still could not cause the cards to malfunction.

So it would seem, from the experiments these guys were doing, the magnetic fields produced from cellphones and fridge magnets are simply not strong enough to damage the infromation on a credit card.

Claude.
 
Yet the cards do seem to loose the ability to communicate... What is it? I am pretty sure that several of mine died after leaving my wallet on the car seat in the sun on a +100F (~35C) summer day. The cards all took the curve of the wallet, and would never again lay flat or work. So apparently heat can do the job.
 
GENIERE said:
Goggle for NU metal.
That would be "Mu" metal; it comes from [itex]\mu[/itex] being the symbol for permeability. NU metal is a type of music :smile:
 
krab said:
That would be "Mu" metal; it comes from [itex]\mu[/itex] being the symbol for permeability. NU metal is a type of music :smile:

Well I hope the OP found some decent NU music sites! :blushing:
...
 
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Thanks for the info; I'll investigate further (both the Mu metals and whether the damage is as extensive as it sometimes seems...)
TheCat
 
Little trick, somewhat related: Sometimes when a card reader is having trouble reading, you might see someone enclose a card loosely in a plastic bag before swiping it again. I've seen it work several times, even with my own cards. I'm assuming that it's using contact electrification/electrostatics to amplify the field on the mag strip (please correct me if I'm wrong).
 

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