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How to Use a Counterfeit Pen to Detect Fake Currency

Written by Robert S. Brown / Fact checked by Helen B. Harris

how to use a counterfeit pen

If you do business with cash transactions, one crucial aspect you must not overlook is protection against fake bills.

Among the various ways to detect fake currency, using a counterfeit detector is one of the most common approaches. Fortunately, learning how to use a counterfeit pen is pretty straightforward – you only need to glide the pen on the bill. If the mark turns yellow, your money is real cash.

What is a Counterfeit Pen? What Does a Counterfeit Pen Do?


A counterfeit pen is a special tool that is specifically made to distinguish fake paper bills from real ones.

At first glance, they appear similar to most markers – featuring slim barrels and felt tips. Some detector tools are dual-ended, having a counterfeit detector pen felt tip on one end and a UV light on the other.

A counterfeit pen’s ink is formulated with some solvents and a proportionate amount of iodine that will change color as you glide it on the surface of the banknote in question.

How Does a Counterfeit Pen Work?


A counterfeit pen works thanks to its iodine content, which produces dark marks and turns brown or black, once used in a bill made with ordinary paper—or, in short, fake bills.

The darkening is due to the redox reaction between the indicator (iodine) to the presence of starch, which is a common additive used in the printer paper manufacturing industry.

On the other hand, banknotes like US dollars are normally made with 75% cotton and 25% linen. This combination is starch-free, so it can’t react with iodine in a counterfeit buster pen. So, when you strike it on a legit banknote, the ink should be a light yellow.

Note that this is not the ultimate test, as counterfeiters nowadays have leveled up and figured out more ways to make fake bills rather than amateur strategies like using ordinary printer papers.

Counterfeit pens are very easy to use. You can use them in the same way you use standard pens and markers. To check counterfeit money with pen, follow these instructions.

Uncap the counterfeit pen. Utilize the blank space near the borders or locate a conspicuous space where there is no print. Make a small mark. If the mark turns yellow, congrats! Your bill is likely genuine.

In case you are checking higher denominations, it is recommended to use a secondary tool to get more accurate results. If your pen comes with a UV light, use it to shine the fluorescent strip and check its colors. We’ll go into more details regarding this method in a later section.

marker to check money

What Are the Limitations of Counterfeit Pens?

  • They will not work on a 1950 bill or older, as these banknotes were produced with different ink and material.
  • They may no longer work on new notes made by counterfeiters. As mentioned above, these scammers may have the means necessary to produce fake bills with cotton and linen.
  • The pens are prone to leaking and contamination. The key element of a counterfeit pen is highly dependent on the ink formulation. Any slight changes may cause false results.
  • They cannot detect bleached and reprinted bills.
  • Newer valid banknotes may falsely be identified as a forgery.

Other Ways to Detect Counterfeit Bills

Using a marker to check money could be the most convenient way to avoid counterfeiting. However, if you’re dealing with a large amount of money, you might want to try other advanced options other than counterfeit detection markers.

  • UV Light Detection Method

counterfeit buster pen

So far, this is the most reliable method of detecting counterfeit bills. You’ll need to shine UV light onto the fluorescent strip on the banknote. Then, compare the resulting shade with a color chart as follows:

  • $5 bill: blue
  • $10 bill orange
  • $20 bill: green
  • $50 bill: yellow
  • $100 bill: red
  • Magnetic Ink Method

This method requires you to get a handheld magnetic detector and rub it against the banknote. If it detects magnetic properties in the ink, it will produce a beeping sound, alerting you that the money is authentic.

  • Examine the serial number

how does a counterfeit pen work

Ideal for people who don’t have a specialized detection tool, this method only requires you to examine the banknote’s serial number. There shouldn’t be any uneven space between the numbers. They should also be perfectly aligned.

Also, compare the serial number’s ink color against that of a genuine note. If the shade is noticeably darker or lighter, it’s likely that you’ve got a fake bill. You can also try to see if you got several notes with the same serial number – a telltale sign that your money is not genuine.

Frequently Asked Questions

How long do counterfeit pens last?

A typical counterfeit pen like the model 3513B1 from Dri Mark can cross off more or less 25,000 bills before its ink runs out.

Can Counterfeit Detector Pens be used on other international paper money?

A counterfeit detector pen will not work on all paper currency from other countries. If you intend to use counterfeit detector pens for other currencies, look for a pen with a Universal formulation.

This formulation can be used for Euro, Swiss Franc, Japanese Yen, Pound, Chinese Renminbi, and other currencies.

Moreover, counterfeit detector pens cannot be used for a few modern bills from countries like Australia, Canada, Mexico, Philippines, and the UK that are made with plastic materials.

Do note that most counterfeit pens manufactured and marketed in the US are generally made for US dollar bill detection. So, always check the label.

Why are counterfeit pens not 100% effective?

The main reason is counterfeit pens are limited to detecting the money’s material only. As such, it’s considered a level 1 detection method, meaning it cannot detect super notes and bleached notes done by a more professional fraud artist.

As mentioned, if you want your detection method to be more efficient, you will have to use additional layers of protection, such as opting to use counterfeit pen light with UV rays.

Does counterfeit pen ink disappear?

Yes, the ink in these pens is meant to disappear by itself. This is because detector pens are made with volatile substances that will eventually get consumed and disappear with time.

When was the counterfeit pen invented?

Counterfeit detector pens were discovered in the late 1980s and were first sold by Office Depot around 1992.

What are the top 5 counterfeit pens?

  1. Dri Mark Counterfeit Money Detector Pens
  2. Hidden Valley Merchandise Money Markers
  3. Dri Mark Counterfeit Dual Detectors
  4. Note Shield Counterfeit Bill Detector Pens
  5. Entrust Pro Counterfeit Detector Pens


Learning how to use a counterfeit pen is not that complex. You just have to remember that a clear or yellow mark indicates a good bill while a dark mark means a fake bill.

While this method might be convenient and practical, keep in mind that it’s not entirely foolproof. So, check them from time to time. Put the cap on when they’re not in use and keep them in a cool and dry area to prevent the ink from drying.

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