Long before becoming one of the Founding Fathers of the United States, Benjamin Franklin was best known for his work as editor -along with his brother James- of the New England Courant, a liberal and satirical newspaper in Boston, and for being the creator of the lightning rod and the bifocals.
But three years before he even married Deborah Reed in 1730, Franklin received an unexpected commission: he was chosen to issue banknotes in the American colonies. "And the truth is that he would also have to be known for his innovative ways of making money," explains Khachatur Manukyan, a professor at the University of Notre Dame.
This researcher from the Department of Physics and Astronomy has analyzed part of the 2,500,000 banknotes that Benjamin Franklin printed in his particular Casa de la Moneda and has come to the conclusion that he used "very original techniques", as he explains in an article published in the journal Proceedings of the National Academy of Sciences.
Manukyan and his team have spent the past seven years analyzing a trove of nearly 600 colonial period bills that were part of the Hesburgh Libraries' extensive collection of rare books and special collections. This paper money covers a period of 80 years and includes money printed by the Franklin printing network as well as a series of counterfeit bills.
"Benjamin Franklin saw that the financial independence of the colonies was necessary for their political independence. Most of the silver and gold coinage brought to the British American colonies was quickly used up to pay for manufactured goods imported from abroad, leaving the colonies without enough money supply to expand its economy," says the expert.
A major problem emerged, however, in efforts to print paper money: counterfeiting. When Franklin opened his printing press in 1728, banknotes were a relatively new concept. Unlike gold and silver, paper money's intrinsic valuelessness meant that it was constantly at risk of depreciation.
There were no standardized notes in the colonial period, leaving an opportunity for counterfeiters to pass off counterfeit notes as real. In response, Franklin worked to incorporate a set of security features that made his banknote distinctive.
"To maintain the reliability of the notes, Benjamin Franklin had to stay one step ahead of counterfeiters," Manukyan said in a statement. "But the ledger where we know he recorded these decisions and printing methods has been lost to history," he adds.
Hence, it has been necessary to use physics techniques to partially restore the way in which that money was manufactured. The researchers used instruments from the Nuclear Sciences Laboratory and four other Notre Dame facilities to take a closer look than ever before at the inks, paper and fibers that made Franklin's bills so difficult to reproduce.
One of the most distinctive features they found was in the pigments. The experts found that the counterfeits have high amounts of calcium and phosphorus, but these elements are barely recognizable in genuine banknotes.
Although Franklin used "lamp black," a pigment created by burning vegetable oils, for most of his prints, his printed currency used a special black dye made from graphite. This pigment is also different from "bone black" made from burned bone, which was favored by both counterfeiters and those outside of Benjamin Franklin's network of printers.
Another of the innovations discovered was in the paper itself. The invention of including tiny fibers in the paper pulp, visible as pigmented scribbles inside the note, is often credited to papermaker Zenas Marshall Crane, who introduced the practice in 1844. But Manukyan and his team found evidence that Franklin was including colored silks long before.
The team also discovered that the notes printed by Franklin's web have a distinctive appearance due to the addition of a translucent material that they identified as Muscovite. The team determined that the future Founding Father of the US was increasing the size of these crystals over time.
The research team theorizes that Benjamin Franklin initially began adding muscovite to make printed banknotes more durable, but later continued to add it when it proved a useful deterrent to counterfeiters.
