They are primarily made from cotton and linen. Tiny colored fibers are added for security. What are they?

The material used for currency, commonly referred to as paper money, is far from ordinary paper. Unlike the wood pulp found in most paper products, banknotes are typically composed of a durable blend of cotton and linen. For instance, U.S. currency is made from 75% cotton and 25% linen, a combination that provides exceptional strength and a distinctive tactile feel, making it resistant to wear and tear from frequent handling. This unique fabric-like composition is crucial for its longevity and ability to withstand circulation.

Adding to the complexity and security of these notes are tiny colored fibers, often red and blue, which are randomly distributed throughout the paper during its manufacturing process. These embedded fibers are a key anti-counterfeiting measure, as they are challenging to replicate through printing or other forgery methods. Some security fibers are visible to the naked eye, while others may be invisible until exposed to ultraviolet light, revealing hidden patterns or colors. This, along with other features like watermarks and security threads, makes it incredibly difficult for counterfeiters to produce convincing fakes.

The evolution of currency from early forms like shells and metal coins to today's sophisticated banknotes highlights a continuous effort to create secure and durable mediums of exchange. While the first known paper money emerged in 7th century China, initially made from mulberry bark, the modern blend of cotton and linen has become a global standard for its resilience. Some countries are now even exploring polymer banknotes, a type of plastic, for even greater durability and enhanced security features.