How an iodine pen reacts depends on the type of paper used.

How an iodine pen reacts depends on the type of paper used.

Regular readers know that in real life I work in information security as a contractor to the federal government. My knowledge of security and understanding what has gone wrong with the various merchants that experienced attacks has had me reconsider the use of electronic transactions. While I do not know the exact details of every system, I know that the state of current practices makes using a credit card more dangerous than carrying cash.

As I was waiting to checkout, the person running the cash register was having difficulties with someone whose credit card was not being accepted. It did not matter what the problem was, the issue was holding up the line. While waiting, the gentleman next on line turned to me and said, “This is why I pay in cash.”

Apparently, my fellow line waiter and I had one thing in common, we both visited the bank prior to doing our shopping. He paid for his purchase with crisp, new currency. Just like my new currency, they were mostly $20 Federal Reserve Notes in serial number order fresh from a pack that was opened in the bank.

When the cashier counted the money, she picked up a pen and drew a line on each note. The pen was a counterfeit detection pen that contains an iodine-based ink used to determine whether the paper used is counterfeit.

These iodine pens test whether the paper is legitimate by checking if the iodine reacts with the starch that is used in commercial paper to make them look brighter. If the paper contains starch, then the ink turns dark indicating the paper is not real currency paper. Otherwise, the mark stays amber on the normal cotton bond paper.

There are two problems with this method of counterfeit detection. First, it is relatively easy to defeat the iodine pen by washing and bleaching a low denomination bill and reprinting a higher denomination on the same paper. By using legitimate currency paper, testing it with the iodine pen will not detect that it is counterfeit.

I remember there was a story on one of the television networks about how counterfeiters bleached $5 notes and passed them off as $20 notes after reprinting them. While searching, I found the following video of NBC’s Chris Hanson as he reported about this on Dateline:

Another problem with using iodine pens is that merchants that use them put their customers in danger who have iodine allergies. Those of us with severe iodine allergies can experience anaphylaxis, a serious reaction whose rapid onset can be so severe that it can cause death. As one of those people with severe iodine allergies, I watched this scene in horror.

Following a discussion with the manager, I consented to using a credit card since this was not one of those retailers that have been in the news for being hacked.

After all the Bureau of Engraving and Printing does to ensure that the new currency is more difficult to counterfeit and how the criminals are getting around these iodine pens by using real currency paper, it is incredible to think that these stores are still using tried but untrue measures for counterfeit detection.

In the meantime, the more serious counterfeiters are bleaching and overprinting $5 notes because as the criminal in the video says, nobody looks!

Image of iodine pen courtesy of The Calladus Blog.

Pin It on Pinterest

%d bloggers like this: