Taizong of the Tang Dynasty said, "Using copper as a mirror can correct your clothes." How to make a bronze mirror bright and reflect people's shadows?

“Use copper as a mirror to correct your clothes; use people as a mirror to know your gains and losses.” This is Tang Taizong’s evaluation of the famous minister Wei Zheng, and it also reflects the role of bronze mirrors in ancient people’s lives. Widely used. Bronze mirrors appeared in the Shang and Zhou dynasties.

The bronze mirrors at this time were all round, with a flat mirror surface, a thin mirror body, and no decoration. They were called "plain mirrors." Later, the mirrors became more and more elaborate, taking on the characteristics of handicrafts. In the late Western Zhou Dynasty, square mirrors appeared, and the decoration became more complex.

In fact, the material for making bronze mirrors is not pure copper, but an alloy of copper and tin, that is, bronze. The "Book of Zhou Li Kao Gong Ji", a document describing the specifications of handicrafts during the Warring States Period, records the alloy ratio for making bronze mirrors: half copper and half tin. Later, people added lead to the alloy. The lead would not shrink when condensed. The front of the cast mirror was flatter and the pattern on the back was clearer, which greatly improved the quality of bronze mirror casting. There are two casting methods for bronze mirrors: "open casting" and "combined casting".

The open type has only one mirror frame (the mold for casting the mirror). During casting, the mirror frame is laid flat and the copper alloy solution is poured into it. The combined casting style requires two mirror frames, a back mirror mirror and a mirror surface mirror. When casting a mirror, the craftsman puts the two mirrors together and slowly pours the alloy solution through a small opening. When the solution cools, the craftsman takes apart the vane and the mirror is cast. So, how do you make a bronze mirror clear and bright so that you can see people's shadows?

First of all, the mirror surface must be polished flat. People first use clay to make a flat object called a "fixing plate", and then put the mirror surface on the "fixing plate" and rotate it gently. After this polishing , the mirror surface becomes flat and smooth. Then, people use fine soil and charcoal to carefully grind the mirror surface to make it more delicate.

Grinding is the most time-consuming and labor-intensive part of making bronze mirrors, and it places high technical requirements on craftsmen. After grinding, the copper-tin alloy mirror surface appears silvery white and has high reflectivity, and the copper mirror is ready for use. In order to further increase the clarity of bronze mirrors, people also use powders mixed with tin, mercury, alum, etc. to grind bronze mirrors. The ground mirrors are almost comparable to modern glass mirrors. Bronze mirrors are prone to rust and require frequent maintenance during daily use. Summary:

In ancient times, polishing bronze mirrors was a specialized occupation. The craftsmen who polished bronze mirrors carried mirror polishing iron and mirror polishing bricks with them to make rusty bronze mirrors as shiny as new again.