General Usage Mont Marte Impasto is a clear drying medium used to create texture and retain brush strokes. Impasto can be mixed with acrylics directly and will not change the effect of the final colour. Because Impasto is a water-based medium it cannot be mixed with oils but it can be painted over with oils once left to dry. Impasto adds an expressive quality to artworks and has the ability to bring painting into the third dimension. Clean up with water.