When did they start using security strips in money?

Security strips, also known as security threads, were first introduced in banknotes in the late 1700s. The first recorded instance of a security thread being used on banknotes was in 1798 when an English papermaker named Benjamin Archer patented a process for embedding fine silken threads into paper. These early threads were typically visible, often woven with colors or patterns, but they were the forerunner to the more modern forms of security strips used in banknotes today.

Over time, the use of security strips in money became more widespread. Various technologies were developed, including the use of metallized threads or strips with intricate designs, which added an extra layer of security and protected against counterfeiting.

In the 1840s, the Bank of England began embedding silk threads in its banknotes, which were difficult to replicate accurately without specialized tools and materials. By the early 20th century, many countries around the world adopted the use of security strips in their currency.

Today, advanced security strips and threads play a crucial role in authenticating banknotes. They can include various features such as holograms, microprinting, color-changing ink, and ultra-violet (UV) reactive designs, making them difficult to replicate and adding another layer of protection to deter counterfeiters.