Because of the different proportion of ginseng skin, they are called cotton material, cleansing skin and special skin (special cleansing skin) respectively. Generally speaking, cotton refers to the paper with raw material sandalwood bark accounting for about 40%, which is thinner and lighter; Peeling means that the content of sandalwood bark reaches more than 60%; The content of sandalwood skin, the raw material of special leather, is above 80%. The heavier the leather composition, the greater the tension that the paper can bear and the better the quality; The corresponding use effect is: the higher the proportion of sandalwood, the richer the ink layers, the better the ink moistening effect, and the more able to withstand repeated rubbing with pen power without damaging the paper surface. This may be one of the reasons why cotton Xuan paper is mostly used for calligraphy and leather paper for painting. It's not that you can't write on clean paper or special paper. Cotton Xuan paper can basically meet the needs of calligraphy (unless your calligraphy style requires repeated painting in the same place with a pen).