What is the Xuan paper used by calligraphers to participate in national exhibitions? How many different colors are there on a piece of paper?

Remember to buy a health promotion, be familiar with the quality of paper repeatedly before participating in the competition, grasp the relationship between the weight of writing ink and the penetration effect, and master the penetration law. In addition, there is a little secret: when there is too much water in the pen, the penetration will soon exceed the range you need. Immediately spread it out with another piece of rice paper prepared in advance (waste rice paper that can be used to practice writing), and then rub it repeatedly on the back of this paper with your palm to absorb excess water, which can quickly stop the penetration.