Using infrared imaging technology, a sketch by Renaissance artist Michaelangelo, of his sculpture “Bruges Madonna”, has been found underneath another of his drawings, and suggests he based the famous sculpture on a male, rather than female, model.
Similar techniques have uncovered erased works by Leonardo da Vinci, Raphael, and other Renaissance artists, with the practice of reusing the same sheet of paper for sketches being common at the time due to its hefty cost.
Renaissance artists often reused the same piece of paper for sketches, because the material was so expensive in the 1500s. They would rub out their drawings with stale bread, an early form of eraser. Using infrared imaging which reveals traces of residual carbon left by charcoal and black chalk, the British Museum has detected the underlying drawings.