there are three types of writing brushes: large, medium and small, and long, center and short. The types of brush can be divided into three categories: soft hair (wool), hard hair (wolf hair) and doubled both brush (mixed sheep and wolf).
yanghao pen is soft and absorbs a large amount of ink, which is suitable for writing pointillism with round and solid performance. The wolf's hair is stronger than the sheep's hair pen, and it is appropriate to write and draw. So we can make a preliminary judgment by looking at the characteristics of specific works. For example, the thickness changes obviously, and the smooth and vigorous official script uses softer sheep hair, while the running script uses more elastic wolf hair. However, it depends on the preferences and skills of specific writers.