Although Nelson did create good reproductions, they could not be perfect reproductions. For example, the ink printed onto real money is not completely absorbed by the paper. This is especially true of the black ink and the color-shifting ink. The ink therefore leaves a texture on the paper that is easy to feel, especially when a bill is new. Your inkjet money will not have this feel, and neither did Nelson's. An easy way around this defect is to crumple up the money so it feels worn.
A more important problem, however, is that some of the inks used by the government are magnetic. Vending machines, for one, are sensitive to these magnetic inks and use them to detect counterfeits. The treasury is also scanning bills regularly to detect counterfeits. According to an article from Wired Magazine, titled "Junior Mints":
As the counterfeit bills get used in vending machines and rejected, or as they make their way into banks, where human tellers can feel the difference, or when they get into the hands of an attentive convenience store worker who rejects them, or when they make their way back to the scanning machines at the U.S. Bureau of Engraving and Printing, they are detected. Once they are detected, that alerts authorities to a counterfeiting problem in a certain area of the country. Heightened vigilance, along with news stories and public service announcements, helps to make detection easier. And eventually the counterfeiter gets caught.
With teenagers who are casually counterfeiting, capture is often instantaneous. Teenagers usually make very stupid mistakes when they create counterfeit bills:
- The colors are off
- The paper is wrong
- They print on only one side
- They give the money to classmates who report the crime
Therefore, punishment is swift and sure.