What angle should the folding pen in calligraphy look good?

What you are talking about is probably the folding of regular script. This folding is not 90 degrees, generally less than 90 degrees. But what is this "degree"? This can't be said, it's not unified. Only when there are more copybooks can we slowly master the structural changes of words in various situations. In short, the structure of a word is tight inside and loose outside, which is different. It is not simply "how many degrees" to make it clear. There are many temporary jobs. Say a word, regardless of the degree. What you write directly is in line with the law and is the most beautiful. My main direction is regular script. I've never considered the angle. I will naturally master the structure of various words in the post. In the post, the main considerations are the starting and closing, lifting and pressing, square, round, tight, dense, back, breathing, wet and dry, etc.