The newly cast mirror has no luster, and it must be polished by mirror coating, that is, reflective materials, in order to shine on people. Generally, the powder of mirror grinding agent (Xuanxi) containing tin is placed on the mirror surface, and then repeatedly ground with felt balls. Because of tin infiltration, the mirror is white and bright.
If the bronze mirror is used for too long, it will look extremely dim, so it needs polishing. In ancient times, grinding mirrors was a special occupation. The other side of the bronze mirror usually has some decorative patterns to beautify it, some pay attention to practicality, and there is no decoration on the back.
As we know, bronze mirrors are made of copper and tin according to the ratio of 1: 1, and copper-tin alloy objects have been rusted after thousands of years of baptism. Ancient mirrors have long been "ashamed to see people". Fortunately, there are exquisite patterns on the back, so that they will not become "mediocre people". Therefore, museum staff will put their backs outward when placing bronze mirrors, which is the best viewing angle for the audience.