Problem description:

If you sign

Analysis:

Since 1960s, there has been a watermark on the RMB in China to help people identify genuine and fake coins.

Watermark was first invented and manufactured by Italian paper experts in the13rd century, and it has a history of nearly 700 years. When making watermarks, they carved patterns on a curtain filled with paper pulp. Because the protruding pattern is different from the concave line of the paper, the original design pattern is displayed on the manufactured paper.

1960 China produced the first domestic water-printed paper. 1963, through the cooperation of craftsmen, artists, sculptors and workers, the first banknote paper with watermark was produced in China, and the most complicated watermark pattern was Tiananmen Square. Since China has mastered the complex watermarking technology, the RMB issued by the People's Bank of China from 1965 has been watermarked with Tiananmen Square and five-pointed star respectively.

Watermark is made by pasting paste between two layers of paper, stamping the watermark head with a die and pasting it. Watermark part of the paper is thicker.