The paper used for banknotes is not like the paper from your printer. In a sense, it might not be paper at all. While most paper is made from wood pulp, the paper used for banknotes does not use wood pulp. Instead, currency paper is primarily composed of cotton and linen, materials more commonly used for fabric production.
Specifics of the dollar:
U.S. currency is not made with traditional wood pulp paper. It contains, among other materials, cotton and linen, as well as a security thread made of polyester.
Currency Paper:
This fabric-like paper differs from wood pulp paper and is much more durable than ordinary white paper. Since a banknote will spend much of its life being folded, crumpled, and slipped into pockets, wallets, and machines, this durability is crucial. The paper used in currency is unique in other ways. The paper used for currency is more than just a printing substrate; it is also an important security feature. While the U.S. Treasury does not hide the presence of cotton and linen in the paper, these are probably not the only ingredients.
Fibers Added to Currency Paper:
When making the paper, at least one other ingredient is added to the mix. Fine red and blue fibers resembling threads are incorporated, providing citizens and law enforcement with a quick detail to check when verifying a suspect counterfeit.
Integrated Security Threads:
On larger denominations, another security feature is added: a polyester security thread embedded in the paper itself. This thread has microprinting along its length, indicating the correct denomination of the note. Although it is not normally visible, the thread can be seen by holding the bill up to the light.
A Chemical Reaction Determines Counterfeit Money:
The paper also has specific physical and chemical properties that help distinguish a counterfeit note from a genuine one. Anti-counterfeit pens, widely used by retailers and banks, are felt-tip markers that use a special ink. When marking genuine currency paper, the ink appears light brown or yellow. When marking something else, like ordinary printer paper, the mark will be dark brown, almost black.
Spotting a Counterfeit Bill:
In addition to the security thread, the blue and red fibers in the paper, and the use of color-changing ink, several other security features make it easier to spot counterfeit bills. The ink used to print a note gives the printing a raised texture—a distinct tactile feature. This same ink is magnetic. The imagery on each side of the note includes details too small to be printed on a regular inkjet printer. In each portrait, extremely tiny microprints read “The United States of America.” All the features and details on a bill contain these authenticity markers and more.
