You're standing at a busy register, or maybe you're selling a used couch on Facebook Marketplace, and someone hands you a crisp Benjamin. It feels okay. Or does it? Honestly, most people just do that quick "hold it up to the light" move without actually knowing what they're looking for. It's a bit of a reflex. But the Secret Service isn't playing around; they've seen some incredibly sophisticated fakes lately, from "bleached" bills to high-end offset printing that can fool a standard detector pen. If you want to know how to check 100 dollar note like a pro, you have to look past the paper and start looking at the physics of the bill itself.
Counterfeiting is an old game, but the tech has changed. We aren't just dealing with photocopies anymore. We're dealing with "supernotes."
The 3-D Security Ribbon is the Real Deal
Look at the blue ribbon threaded into the paper on the front of the bill. It's not printed on. It's woven. If you tilt the note back and forth while focusing on that blue strip, you’ll see something kinda trippy. The bells change to 100s as they move. When you tilt the bill vertically, the images move horizontally. When you tilt it horizontally, they move vertically.
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Most counterfeiters can't replicate this because it involves micro-lenses. Imagine nearly a million tiny lenses inside that single strip of blue. It's one of the most expensive security features the U.S. Bureau of Engraving and Printing (BEP) has ever implemented. If that ribbon feels flat or the images don't shift with that specific "parallax" effect, give it back. It’s fake.
The "Feel" of the Paper (and Why Pens Lie)
People swear by those amber-colored detector pens. Here's the truth: they are basically just iodine. They react to starch. Real U.S. currency isn't paper; it’s a 75% cotton and 25% linen blend. It doesn't have starch. So, if a counterfeiter uses high-quality starch-free paper, the pen stays yellow, and you get robbed.
You've got to use your fingernail. Run it across Benjamin Franklin's shoulder. The printing process used by the BEP—called intaglio—leaves a distinct, raised texture. It should feel "scratchy" or rough. Most fakes feel unnaturally smooth or "waxy" because they are printed using inkjet or laser printers that lay the ink flat.
The Bell in the Inkwell
There is a copper-colored inkwell next to Franklin. Inside it is a bell. This is a color-shifting feature. If you tilt the note, the bell changes from copper to green. This creates an effect where the bell seems to appear and disappear within the inkwell. This is a "tilt-to-check" move that takes two seconds but is incredibly hard to forge.
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Watermarks and the "Bleached" Bill Trap
So, here is a scary one. Criminals take a real $5 bill and soak it in chemicals to remove the ink. Now they have a blank sheet of genuine, $100-feeling paper. They print a $100 image on top of it. Your detector pen says it's real. The texture feels okay.
How do you catch this? The watermark.
Hold the bill to a light source. You should see a faint image of Benjamin Franklin in the blank space to the right of the portrait. If you are looking at a $100 bill and you see Abraham Lincoln’s face in the watermark, you are holding a bleached $5 bill. Always match the face in the watermark to the face on the bill. No exceptions.
The Microprinting Mystery
If you happen to have a magnifying glass—or just really good eyesight—look at Franklin’s jacket collar. You should see the words "THE UNITED STATES OF AMERICA" in tiny, tiny letters. Check the blank space where the watermark sits; you’ll find "USA 100" repeated there.
Counterfeiters struggle with this because their printers lack the resolution. On a fake, these letters usually look like a blurry, solid line or a series of dots. It’s a "dead giveaway" for anyone who takes the time to actually look.
The Security Thread
There's another thread, distinct from the blue 3-D ribbon. This one is vertical and embedded in the paper to the left of the portrait. It says "USA" and "100" in an alternating pattern. If you hold it under a UV light (blacklight), this specific thread should glow pink. If it glows any other color—or doesn't glow at all—it's a dud.
What to Do If You Find a Fake
It happens. You realize the bill in your hand feels like a napkin or the "100" in the corner doesn't shift from copper to green.
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- Don't put yourself in danger. If a customer gives it to you, don't play hero.
- Observe the person. Remember what they look like or check your security cameras.
- Handle the bill as little as possible. Put it in an envelope. The Secret Service can actually pull fingerprints off these.
- Contact the authorities. Call your local police or the nearest U.S. Secret Service field office.
Honestly, the best defense is just being observant. Most people get caught because they are in a rush. They see the big "100" and the face of a Founding Father and assume it's good.
Next Steps for Your Business or Personal Safety:
Go get a small UV flashlight. They cost about ten bucks online. While the 3-D ribbon and color-shifting ink are the "gold standard" for checking, that pink glow from the security thread is an instant, undeniable confirmation. Start checking every high-denomination bill that passes through your hands. Once you know what a real $100 feels and looks like, the fakes will start to stick out like a sore thumb.