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How does light exposure change the colours in paintings and works on paper?

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Inside the ongoing preservation of the Vatican — Art conservation and restoration Learn about the restoration of tiles in St. Peter's Basilica, Vatican City.

Prolonged light exposure causes irreversible damage to paintings and works on paper, primarily through the fading of colorants and the darkening of the paper support. This degradation is cumulative, meaning that even low-intensity light exposure over time results in permanent changes to the artwork.1

When colorants fade and the paper support darkens, the original contrasts intended by the artist are significantly skewed, leading to a loss of depth and detail. The ultraviolet component of light is particularly damaging to these organic materials. Because this damage is both cumulative and irreversible, art conservators emphasize the importance of limiting light exposure through prudent monitoring rather than relying solely on protective measures like UV filters.1

The ability of a material to resist these changes is known as lightfastness. To preserve the integrity of an artwork, it is essential to avoid daylight exposure and maintain strict control over the total quantity of light to which a piece is subjected.21