Chinese ink is not pigment. It has five colours: Coke ink，thick ink, heavy ink, light ink and light grey ink. The main materials are carbon black, pine-wood soot，glue with precious traditional Chinese medicine and spices etc. Ink is ground with inkstone water to produce ink for painting, which exists in colloidal solution in water. Carbon black is the main material of ink in Chinese paintings and charcoal in Western sketch. Because sketch is preconceived, my works are easily mistaken for sketch.