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Glossary · Technical Analysis
Infrared Reflectography
An imaging technique that uses near-infrared light to see through finished paint layers — revealing underdrawings, pentimenti, and earlier compositional states invisible to the human eye.
How It Works
Near-infrared radiation (wavelengths of roughly 1,000–2,200 nanometres) penetrates most paint layers — including lead white, earth pigments, and many organic colors — and is strongly absorbed by carbon-based materials such as charcoal, black chalk, and carbon black ink. This means that an underdrawing made in charcoal or black chalk is "opaque" in the infrared even when covered by many layers of paint.
An infrared-sensitive camera or scanner captures this signal, producing images that reveal the drawing beneath the finished surface — as if the paint had become transparent.
Significance for Leonardo Studies
Infrared reflectography has transformed Leonardo scholarship since its widespread adoption in the 1970s–1990s. Key discoveries include:
- Mona Lisa: Earlier hand position; traces of columns in the background; evidence of the parapet extending further
- Virgin of the Rocks (Louvre): Dramatic differences between underdrawing and final painting — the angel originally pointed in a different direction; the positioning of figures was substantially revised
- Salvator Mundi: Infrared imaging revealed Leonardo's underdrawing and multiple pentimenti, supporting its attribution
- Lady with an Ermine: Showed the ermine is a late addition not in the initial underdrawing