Paper money was only the promise of value, so people had reason to be more skeptical of early banknotes. Creating a reliable cash currency has meant fighting against counterfeiters. Serial numbers, sophisticated plate engraving, special paper: central banks have used all kinds of techniques to create authentic banknotes that can be distinguished from fakes. One eighteenth-century option was marbling.

Marbling, the printing of a marble-like pattern on paper by floating dyes on a water bath, was a technique that had been developed in Persia and India before spreading throughout the Ottoman Empire. When it made its way to Europe, it appealed to both artists and London's world of financiers, who used it on banknotes and bonds. As historian Jake Benson describes, the idea caught on fairly fast:

Difficult to replicate, marbling was a way to make banknotes and checks unique. When the United States was trying to create its first currency, Benjamin Franklin brought to the table the idea of marbling as a security technique, based on his experiences with in London. Subsequently, Franklin writes Benson. More significantly, he also used the technique to safeguard

Those promissory notes-exchanged for hundreds of thousands of French livres-were critical for an aspiring republic that struggled to feed and clothe its army.

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