Impasto (Italian: 'dough') describes paint applied so thickly that it retains the marks of the brush or palette knife — creating a texture that can be seen and even felt. It is the opposite of glazing, in which thin transparent layers are built up slowly. Titian used it to suggest weathered flesh; Rembrandt used it in his late portraits to create surfaces of extraordinary density and life. But the technique's greatest practitioner was Van Gogh, who used impasto with almost violent intensity: the swirling surfaces of The Starry Night or his self-portraits have a physical energy that reproduction never fully captures. Modern expressionists — Lucian Freud, Frank Auerbach — carried the tradition into the 20th century, applying paint so heavily that paintings took months to dry.