The sooty black pigment in India ink has an extreme fineness of less than 2 microns (1 micron = 1 /1000 mm). These particles are in constant motion in the ink, colliding and repelling each other. Due to the special ink preparation method, they do not clump together. However, if a large amount of water is added to the ink too quickly, the binder (shellac) surrounding the particles dissolves. The particles then clump into larger particles and sink to the bottom. When diluting the ink, the water should therefore be added and mixed little by little to avoid this phenomenon.