The type of brush you choose with gouache paints will depend on the effects you want to achieve. Soft round brushes are a good choice for washes, layering and general painting, while flat brushes are better for creating even washes and blocking in large areas of colour. As the name suggests, detail brushes are ideal for adding fine details, lines, and accents. More broadly, synthetic brushes are generally better for gouache than natural hair brushes because they hold their shape well and are easier to clean.