How to Spot a Counterfeit Bill: A Guide to Detecting Fake Currency

It's estimated that one in every 10,000 bills in the U.S. is a fake, adding up to millions of dollars. Counterfeit money can cause significant problems, from personal financial loss to destabilizing national economies. Fortunately, anyone can help catch counterfeiters with a few simple tools and a bit of knowledge.

Detecting Counterfeits: Tools and Techniques

The Anti-Counterfeit Detection Pen

This pen, resembling a highlighter, contains a solution of potassium iodide and elemental iodine. It works by detecting the presence of starch, which is commonly used to strengthen regular printer paper. Authentic bills, however, are made of cotton and linen and are threaded with tiny red and blue fibers. This unique material is produced by Crane and Company, a highly-guarded company that has been printing currency since the Revolutionary War.

• How it works: Counterfeit bills often contain starch made of amylopectin and amylose. Amylose, with its long chain of sugar molecules, forms a helical structure. Iodide squeezes inside this coil, forming a compound that leaves a dark mark on the paper. If there's no starch, the mark will be light yellow.

UV Light Examination

U.S. bills printed since 1996 have been chemically enhanced with a strip that fluoresces under UV light. This is the same type of light used at black light parties and airport security.

• The Security Strip: The polyester strip, printed with invisible ink, is just one millimeter wide and is located in different positions depending on the bill's value. Holding the bill up to natural light reveals the amount and the word USA printed on the band.
• Fluorescence: Under UV light, the strip glows. The molecules in the strip absorb energy from the UV light and then radiate the rest as visible light. If a glowing strip doesn't appear on a recent bill, it's likely a fake.

Visual Cues for Spotting Fakes

Even without special tools, you can look for simple visual cues to identify counterfeit bills:

• Portrait: Ensure the portrait looks lifelike and not flat.
• Seal: The seal should have perfectly even sawtooth points.
• Border: The inked border should be unbroken.
• Serial Number: The serial number should have precisely equal spacing between each number.

The Chemistry Behind Counterfeit Detection

The use of iodine solutions and UV light relies on basic chemical principles. The iodine reacts with starch to create a visible mark, while UV light excites molecules in the security strip, causing them to emit visible light. Understanding these principles can help you better detect counterfeit bills.

Conclusion

By using anti-counterfeit pens, UV light, and careful visual inspection, you can protect yourself from counterfeit currency. Stay vigilant and remember these tips to ensure you're not caught off guard by fake money.