Adjustment of calligraphy ink color

It's not the writing, it's the ink. Think about it, can you write for the sake of writing black? In addition, if you are practicing calligraphy instead of selling calligraphy, you don't need to pursue ink color. You should learn more about brushwork and structural expression. But ink color has something to do with using a pen, which is the only way for a center. Even if some great calligraphers in history have many "good" tendencies, it is also his personal preference and style expression, not to say that he can't play center.