What type of counterfeit detection method can be used on currency?

The method known as a detector pen is specifically designed for quick and easy identification of counterfeit currency. These pens contain a special iodine ink that reacts with the starch present in paper that is typical for counterfeit bills. Genuine currency paper does not contain significant starch, so if the pen leaves a dark mark, it indicates that the bill may be counterfeit.

While other methods such as visual inspection, watermark checks, and UV light tests are also effective in detecting counterfeits, the detector pen provides a straightforward, accessible, and immediate means for cash handlers to verify banknotes during transactions. This makes it a favored tool for businesses and individuals who handle cash regularly.