In suminagashi (Japanese paper marbling), the earliest and simplest form of marbling, inks are applied to the surface of the water with tapered brushes. The ink floats and the water urges the spots of colour into concentric bands (as depicted in the image below):
9 Paper Marbling Tutorials That You've Been Waiting For
Rediscover Suminagashi: An Ancient Japanese Painting Technique Suminagashi, which literally means "ink floating" is an ancient Japanese technique of painting on water. The ink or paint is then transferred to paper or another absorbent material and allowed to dry. This technique is often referred to as "marbling", as well as Ebru. These days, you can use inks, acrylics, oils, and even nail polish with this painting technique to create truly interesting and unexpected results!