I mentioned the findings in Cecil’s column on eelskin wallets to a co-worker
Aha! Tested by actual experiment!
My co-worker replied that Mythbusters had done the same thing and declared the myth busted:
From the Wiki entry on this episode:
The implication is that you wouldn’t encounter magntic fields strong enough to demagnetize your cards, and it’s elsewhere stated that they had to find one of Jamie’s neodymium magnets to wipe the card.
But Katie of Citicorp’s in-the-wallet magnet was capabvle of wipin cards from 2" away!
Did anyone ever find out why such humongous magnets were being used?