How Does a Blotter Take Up the Ink of a Blot?

It is because the blotter has a very excellent ability to absorb some liquids. The thinner the liquid the more easily the blotter will absorb it. Ink is thin—being mostly water—the blotter is of a loose texture and has a rough surface. This gives the blotter the ability to pick up the ink, just as a sponge would do. A sponge has what is called the power of capillary attraction and so has the blotter.