What is Watercolour Painting? Using a water-soluble medium, watercolour painting is the process of creating art through the suspension of pigments. A natural adhesive known as gum Arabic, which is derived from the sap of the acacia tree, is usually mixed with the pigment. A brush is used to apply the mixture onto a painting surface, typically paper. When water is added to the pigments, they dissolve and can be spread across the surface, creating a range of effects from light