When the U.S. Civil War broke out in 1861, The central government did not have the resources to force the rebel states back into the Union. The Lincoln Administration and The Congress of the time were forced to use paper money and the printing press to finance the North’s war effort. Unfortunately, the North didn’t have the printing presses to even print their fiat currency.
The Lincoln Administration turned to the American Bank Note Co. in New York City to supply its currency needs. Deterring counterfeiters was in The U.S. Treasury’s upper mind. For this they paid extra to use ABNCo’s patent “Canada Green” ink security tint guards on the paper note faces. A similar, but non-patent green ink had been used on other note backs, hence the nickname “greenbacks.” Early greenbacks have the patent date “30 June 1857” on the note faces.
The patent was held by the inventor of the green ink, Canadian Thomas Sterry Hunt, and the license holders to the patent who claimed that the ink would indeed be able to deter counterfeiters. The green ink could not be chemically leached from the printing paper without destroying the companion black ink in the process, thus foiling would be counterfeiters.
It was the hope of the Federal Government that this ink’s immutability would make it impossible to also copy the note by photography, which was often the method of choice for counterfeiters of the day in order to piece together a set of fake currency plates. Unfortunately the patent Canada Green Ink didn’t hold up to expectations. It was in fact, not immutable as claimed. Unfortunately the counterfeiters were smarter than Mr. Hunt, as they had little trouble clearing the ink from the notes.
The Associated Banks for the Suppression of Counterfeiting tested out the patent claims and found out that even amateurs could easily remove the green ink without harming the black impression or destroying the underlying paper. This confirmed what many shady pressmen already knew.
With the counterfeiters outwitting the makers of the “Green Ink,” other chemists went back to the drawing board so to speak. Given the overwhelming prevalence of $10 and $50 fake notes, the Feds tried to keep a step ahead of the counterfeiters. Their next response was to use a new and truly immutable green ink in the printing process.
On some 1863 notes, the contractor experimented with this new patent green ink on both the $10 and $50 note faces printed up by the American Bank Note Co. They adopted Asahel K. Eaton’s chromium ink which had a patent date of April 28, 1863, in place of the ABNCo’s anti-photographic “Canada Green” ink. Unfortunately it didn’t work any better than the “Canada Green Ink.”