In ancient times, some calligraphers and painters used ink to write and draw. After thousands of years of calligraphy and painting, the ink is still clear. Why?

There are good and bad inks. For example, the good ink of Cao Sugong of Yidege, with natural ingredients and lasting secret recipe, is preserved by later generations and is not easy to fade and mildew. Calligraphy and painting have been preserved for thousands of years, and it is really commendable that they are as old as new. After the changes of the world, China's 5,000-year-old cultural and artistic heritage is profound and valuable.