What is Metamerism?

Metamerism is the phenomenon where two colors appear identical under one light source, but visibly differ from each other under another light source. The classic example: you think you're wearing two black socks, but at work one sock turns out to be dark blue. Under daylight they were identical; under artificial light suddenly not anymore.

Metamerism occurs frequently in color production, quality control and product development — especially when multiple components together must form one uniform end product.

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The Cause of Metamerism

Whether two colors appear identical depends on three factors:

1. The light source – each light source has its own spectral composition.
2. The object – materials reflect light in a unique way (reflectance curve).
3. Our perception – the visual system forms a global impression based on that reflection.

Two colors can have different spectral reflections and still look the same under one light source. As soon as the light source changes, a visible difference emerges.

A characteristic of a metameric color combination is that the spectral curves typically cross three times.

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Types of Metamerism

1. Illuminant Metamerism (most common)

Two colors appear identical under light source A (for example daylight), but differ strongly under light source B (for example fluorescent light or incandescent light).

2. Observer Metamerism

Two people can assess the same colors differently due to variations in their visual system (for example due to age, color deficiency or lens opacity).

3. Material or Wet/Dry Metamerism

The same coating or textile can wet give a different color impression than dry, because the surface reflects light differently. Different pigment or binder types in components also cause this type of metamerism.

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When Does Metamerism Primarily Occur?

Metamerism occurs more often in:

• neutral color groups such as gray, white and black
• materials with different pigment sets
• products with components from different suppliers
• substrates with fluorescent whitening agents (such as paper or plastics)

The more saturated the color, the smaller the chance of a metameric match.

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How Do You Prevent Metamerism?

1. Use light booths with standardized light sources (D65, TL84, A)
2. Work with identical pigments and consistent formulation
3. Assess both visually and instrumentally (spectrophotometer)
4. Establish tolerance agreements in the chain (suppliers → manufacturer → end customer)

By assessing colors under multiple lighting conditions, it can be determined early whether metamerism poses a risk.

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Want to Learn More About Metamerism, Light and Color Assessment?

In the trainings of the Dutch Color School you will learn:

• how metamerism occurs and how to recognize it
• how to work with standardized light sources
• how to combine visual and instrumental assessment
• how to ensure color quality in production chains

👉 Want to learn more? View the trainings at: https://kleurenschool.nl

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Questions about metamerism, light sources or color assessment? Contact the specialists at Stichting Nederlands Kleurinstituut: https://kleurinstituut.nl/contact