You tilt the brush at a certain angle to the right, and then draw it down (not too long). It's called sidestroke.
Comparing the two, you will find that the line in the center is more powerful. Center stroke is the main operation mode of writing with brush. When the brush runs on paper, the belly of the pen is in front of the running, and the nib is behind the running. The nib is always repeated on the ink formed by the belly of the pen, and the pen is transported as the center. When the pen is carried in the center, the direction from the pen tip to the pen belly is consistent with the running direction of the brush.
Because of the different writing strength and speed, the strokes written in the center will have different textures. It can be roughly divided into two categories: one is that the edges of strokes are smooth and smooth, such as knives, which were called "ancient hairpin feet" in ancient times; Another kind of strokes with rough edges, such as Wannian rattan, was called "leak mark" or "golden stone gas" in ancient times. The former writes a little faster, even harder, showing the beauty of vigor and power. The latter has a slightly slower writing speed, greater power and slightly trembling fingers, showing the beauty of vigor and maturity. Beginners practice the neat lines in front first, and then pursue "leakage marks" when they are proficient. In fact, the "leak mark" is natural, not man-made, and it is impossible to achieve it by trembling or twisting deliberately.
The ancients often used "through the back of the paper" and "through the wood" to describe the lines of strokes. The so-called "force through the back of the paper" means that when writing, the pen is strong and the ink can penetrate the back of the paper. The teacher checks whether the students' calligraphy is serious, and often turns over the book paper to see if the ink in the middle of the strokes is understood thoroughly. If the two ends of the stroke are as black as the middle, it shows that the student is serious and not careless. If it is found that the head and tail of the stroke are black, but the middle part is not black, it means that the student wrote carelessly and passed it by. "Three points into the wood" comes from Wang Xizhi. He wrote a sacrificial prayer board (wooden board). Because he wanted to rewrite a new message, he asked the carpenter to cut off the words, and as a result, he cut off three points before the ink disappeared. It shows that Wang Xizhi's brushwork is vigorous, and his pen and ink can go as deep as the chessboard. "Through the paper back" and "through the wood" are all about the strength and ink color of the center.