Why is the high and low frequency sealed with a stamp?

In ancient China, cinnabar was recognized and applied earlier. Its chemical composition is mercury sulfide and its color is vermilion, which has long been used as a pigment. As early as the Shang Dynasty, Zhu Jiagu was painted, and vermilion was ground into red powder and embedded in the notch of Oracle Bone Inscriptions to show its eye-catching. The application of cinnabar modulation printing color in bronze printing was invented in the Warring States period, but its application scope is limited.

In the eyes of the ancients, red was considered sacred. For example, amulets, spells or magic divination are usually written in red, which is considered better and more effective. The imperial edicts are often written in red ink.

In addition, because the red seal is not easy to fade, eye-catching and solemn, it is not only solemn, but also authoritative and deterrent. Therefore, most of the seals we see are red.