Concept · Foundations

Metamerism

Metamerism is when two colors match under one light but not under another, because their surfaces reflect different mixtures of wavelengths that happen to look alike.

The eye reduces every mixture of wavelengths to three cone signals, so quite different mixtures can give the same three signals. Change the light and each surface shifts by its own amount, so a passage matched under studio lamps can stand apart in daylight.

• Check an important match both by daylight and under the light where the work will hang.
• To match an earlier mixture, or to retouch, use the same pigments, not just a color that looks the same.
• Viewers differ too: a pair that matches for one person may not for another, because cone responses vary.

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