What is the frost on the ink in ancient calligraphy?

That's because you have to brush the ink on the stone carving when rubbing. Due to the natural weathering of stone carvings over time, the surface of the carved characters is not smooth, so it can't be brushed with too much ink, and it will drip, which will eventually affect the texture of its rubbings. New friends in calligraphy, please answer your questions and adopt them!