Potassium Alum-MingFan

Ming-Fan (明矾)  is widely used in Meticulous work by Chinese artists. Some artist found the shop brought paper  or silk which have uneven Alum on paper or silk. They found it helps if they add on (brush in) with diluted Alum onto the work surface (Xuan), it enables a evenly brush-strokes on the thin Xuan. Occasionally, it adds on to some heavy mineral pigment (ie. Red)  the mixture is enabling the heavy pigments fixed better on Xuan(paper).