Cao Sugong is oily tobacco ink, produced in Shanghai, with musk. All the ink for painting and calligraphy can't be put back in the bottle, and it won't take long after it is poured out. Because ink will be oxidized, fine particles will appear when it is not used for a long time, and the color of ink will become dark. Don't ignore small particles. When small particles are sprayed or embedded in water, they will also be stained with ink to form a picture. The ancients said that the so-called Su Mo could not be used. That's the reason. I suggest you pour out the ink, grind it with an oil smoke ink stick until it becomes thick, and add a proper amount of water while using it, which not only changes the ink color, but also has a bright ink color. ...
Moreover, the lid of the small pot on the Cao Sugong ink bottle must be sealed tightly, so as not to affect the quality of ink. The longer the ink is kept, the better. I think you will understand. ...