Is it difficult or easy to penetrate cardboard? What happened?

This situation has little to do with the quality of paper and ink. There are two reasons for this:

1, the water content of the ink is too large, and the penetration is serious when writing;

2. The ink is too full, and the running speed on the paper is not fast enough, which causes the ink to drip and penetrate naturally. Solution: 1 Control the water content of ink. If it is self-grinding ink, you can continue grinding without competing with water until there is a proper amount of ink on the brush to write normally; If it is the current ink, you can add thick ink or use less ink. 2. Wrap the pen belly with absorbent materials such as tassel paper or rice paper, and use it after absorbing excess ink; If the brush is not particularly full, it can run quickly on the paper to reduce ink blooming.