An unusual lead compound offers a clue to the extraordinary body of his impasto.
How could Rembrandt apply oil paint so thickly that it held every ridge, stroke, and raised highlight instead of slowly spreading across the surface?
The answer may begin with the chemistry of the oil itself.
Impasto is paint applied thickly enough to rise above the surface. Brush or palette knife marks remain visible, and real light catches their edges. Rembrandt often placed impasto in illuminated areas while keeping many shadows thin and transparent. This contrast makes the lighter forms appear to project toward the viewer. …