Model Wash colors are liquid, transparent paints designed to create aging and weathering effects on armor, vehicles, aircraft, ships, figures, and other miniatures, as well as on dioramas. All surfaces exposed to sun, wind, dust, rain, and snow undergo a change in their hue: a loss of intensity, dulling, and general fading. For model painters, reproducing these changes can be challenging. Washes are the perfect solution to achieve these effects.

The Wash colors can be mixed together to create further variations in shades; they can be applied with an airbrush or a brush, depending on the requirements and the desired effect. Washes are also very suitable for delineating the edges of camouflage colors from the base color of a model. They can also be mixed with pigments or acrylic paints to depict a wide range of effects such as oil, rust, mud, earth, dust, moss, and more.

Vallejo Wash colors have been formulated with an acrylic resin to ensure that the surface tension is similar to that of traditional solvent-based washes and filters, but with the advantages of a water-based medium. The average drying time for Wash colors is about 20 minutes. If multiple layers are to be applied, it is best to wait about 40 minutes between applications. Painting tools should be cleaned with water.