5. The Paper
Real bills have tiny red and blue fibers embedded in the paper, and counterfeiters have tried to replicate those. Ink marks can be printed onto the paper to look like hairs, Kersten said. He also noted that people have used cat or human hair that is dyed red or blue to embed into the bill. At close inspection, however, it is clear that the hairs are on the surface of the fake bill and not embedded into the paper. “But most people don’t even look for the hairs anymore because you have to look really closely,” Kersten said. “That is why the government put bigger things to look for in [the bills].”
At many grocery and convenience stores, clerks will use an iodine-based counterfeiting pen. The pen reacts to the starch in the paper. If the bill is real, the ink turns yellow. But if the bill is counterfeit, it will turn a dark blue or black. “Most counterfeiters don’t bother to use starch-free paper. They just use paper that simulates the color, thickness and look of real currency,” Kersten said. “But if your counterfeiter is good, they will use starch-free paper.”
7. The Feel
The feel is probably the most common way that people detect counterfeit, Kersten said. Real currency has a “raised texture” to it because of the type of press used to produce the bills. Counterfeit bills feel flat because they are often made digitally or on an offset press. People who handle a lot of cash “can just notice that something doesn’t feel right,” Kersten said. From there, other factors can be used to determine whether a bill is counterfeit.
8. The Watermark
The watermark is the shadow of the portrait that appears when you hold the bill up to light. “That is one of the easiest ways for the common citizen to identify counterfeit versus genuine,” DeSantis said. Periodically, there are people who attempt to recreate the watermark, he added, but it tends to be of very poor quality. The people who do try to imitate the watermark use bleaching, Kersten said. People at stores usually only care that there is a watermark within the bill, he noted, but the watermark portrait must actually match the printed portrait to be genuine.