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Change For A Hundred?

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16 comments to Change For A Hundred?

  • I spent multiple years managing teenagers and twenty-somethings in retail, and at the time I had no clue that the pen was bogus, and we insisted that every large bill be marked. One time I was counting down the register and found a $20 bill that was photocopied on printer paper and sent through the laundry or something. I mean, it was ridiculous, not even quite the same size as an actual bill. It might as well have had a cartoon moose in the center. I showed it to the cashier and asked her what she was smoking. She shrugged and said it was fishy, but they were only supposed to mark the large bills so she didn’t bother.

    From then on, cashier training changed to highlight common sense first, counterfeit pen second.

    Oh, and the same girl once used the counterfeit pen to trace and color in a giant “420” on the back of a $50 bill. My god she was stupid.

  • Hah, interesting, I’d never heard of that kind of thing. Maybe it’s that I come from a place where the pen isn’t used, but personally I’d put much more trust in the watermark and embedded strip. Seems to me that it would be more likely to produce false positives than to actually reveal fakes. Wouldn’t a fake note printed on regular paper be fairly obvious even without a pen?

  • DLC

    Unfortunately all too many retail stores use these stupid pens. Between all the security features in the currency, anyone with decent eyesight and five minutes worth of education on what to look for can spot a genuine bill. But, too many people, including store managers, rely on the silly pens.

    For Rebecca:
    Did you ever wonder if the “420” fans realize
    they’re getting high at a time equivalent to Adolf Hitler’s birth month and day ?

  • Jim Shaver

    When I was on vacation a few weeks ago, I noticed U.S. $1 bills with famous people’s faces in place of Washington’s for sale in a gift shop. (I don’t remember the exact cost, but I think they were $2 or $3 each.) The sign said that they were valid U.S. currency. I looked carefully through the glass and noticed that the new portraits were actually stickers cut out and placed precisely on the bills. Therefore, since the stickers could be removed, the bills were not technically defaced.

    I wonder how the typical cashier with a counterfeit-detection pen would react to, say, a real “hunj” with Sly Stallone’s face in the center. (I think it would have to be either a one or a hundred, since the other denominations do not have a nice oval frame around their portraits.)

  • SkepGeek

    The pens have a high false positive rate as you argue, but what of their false negative rate. That is all the retailer really cares about. If they misidentify good money as bad, it does them little harm.

  • icon

    Sometimes when I am at a store, I am tempted to ask to borrow the clerk’s counterfeit detecting pen and check all the paper money he or she is giving me with my change.
    Or maybe what I really need is a pen of my own that looks like the real thing, but which is rigged to give a positive or negative result at will, so I can randomly reject some of the change I get, just to be annoying and difficult.

  • Here in Canada we use black lights to reveal phosphors hidden in large bills. Seems a bit more foolproof than the iodine pens (which I have never heard of till today). Canadian money is (and has been for a while) years ahead of American money.

    Also, it’s ridiculous that a $100 bill and a $1 bill look so much alike, why not use different colours?

  • chucklenose

    What are store policies when they suspect a counterfeit bill? According to the treasury department (http://www.ustreas.gov/offices/domestic-finance/acd/if-you-suspect.shtml), they are to call the authorities, keep the bill and try to detain the passer. With the possibility of false positives, this raises some real legal issues for the store as well as for their customer losing the bill they just tried to buy a stick of gum with.

  • DevoutAtheist

    Thank you for the post – I had never thought about how that pen works (or does not work).

    If someone were evil, or just wanted to pull a nasty April Fools joke, all they would have to do is exchange a 50 or 100 sprayed with ye olde ironing starch with someone they did not really care for, and then watch the fun!

    (BTW – I am neither evil nor a proponent of nasty 4/1 jokes, nor am I suggesting someone do it…. but they could.)

  • waltdakind

    I also used to make a point of always attempting to educate people on the uselessness of the pens. I got the same response, “uh-huh”.

    Eventually the apathy got to me and now I usually watch the use of the pen without comment.

    It’s a shame they’re continuing to be sold.

    Though one can’t really sue the company, as they do readily admit the detectors are counterfeit. It says right on the packaging “counterfeit detector”.

    How’s that for truth in advertising?

  • Hi Evan,

    Slightly off topic, but regarding security of financial transactions, it’s totally worth reading the saga from the guy at Zug who was so ticked off about people accepting ‘bogus’ credit card signatures that he started a campaign of seeing exactly how far he could go before the signature would be rejected (heiroglyphics was just one accepted sig). I think you’ll be very surprised. But perhaps not.

    Plus it’s VERY funny.


  • jdub

    Great examination of a topic where simplicity has replaced common sense. Currently I am a restaurant manager and the upper management has instituted the use of these pens for checking large currency, they pass most fakes. As Evan was saying there are a large number of features to guarantee that the bill is genuine, the best is the feel of the bill, it has raised printing that I have never seen, yet ,in a counterfeit. So far I have seen counterfeiting including the water mark, security strip, and color changing ink.

  • wastrel

    Wait, a convenience store actually took a $100 bill? I can’t get ANYONE to take a hundred.

  • dangerousbirde

    Oh the joys of working in retail. I’ve been the teenager behind the counter for many years. Not that I’m in college though I suppose I’m just that guy behind the counter. And Evan you can’t be too hard on him, I mean he’s probably just waiting to go home and some guy starts asking him weird questions, which happens more than you might think in retails, anyways this is beside the point.

    One of my first experiences checking a bill to see if it was real was horrible. I had the pen but had not been told exactly how it worked yet. I had somebody paying with a large bill and I marked the bill, and the ink turned amber. It could have turned purple with red edging and not mattered, I didn’t know what each color meant. So using my critical thinking skills I grabbed a piece of paper from my register and marked that. Assuming that whatever color the paper would turn would be the color marking a fake. Well turns out the paper I use using had a high fiber content and no starch whatsoever. Needless to say when I informed the customer of my little experiment they weren’t too happy.

    This was about five years ago and I haven’t used a pen test since. In fact I’ve been informed from a couple of sources that what counterfeiters do is wash and reprint five dollar bills rendering the pen test absolutely moot.

  • esmitt

    I’m with Johnny_eh about the colours. Seriously! The US currency has got to be the most copied in the world. Get another colour on there and change it once in a while…oh yeah and also get rid of the ones and replace them with coins.

  • joelmael


    You estimated the age of the clerk as not more that 17. What is pertinence of his age to your discussion of the pen?

    Would it be pertinent to estimate the age of a person of middle or old years?

    I am 73. Do you think my age is a significant aspect of my comment?

    How old are you? Who knows, some of us may think we should know your age in or to properly evaluate your article.


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