A transparent layer of graphene only a few atoms thick can prevent pigments in paintings from fading by protecting them from ultraviolet light, moisture, and air pollutants.
Color fading is a big problem for painted works of art. Vincent van Gogh is famous sunflowers For example, paintings contain light-sensitive lead pigments. Originally bright yellow, they have turned greenish-brown over time.
A graphene haze can prevent up to 70% of the fading of the color, the researchers suspect behind the work. While the exact amount of protection depends on the colors and the pigment substrate, “this corresponds to an exposure of around 200 years under the conditions found in museums or other exhibition environments,” says study director Costas Galiotis from the Hellas Foundation for Research and Technology in Greece.
“Depending on the number of layers, graphene absorbs a considerable amount of ultraviolet light and is a very good barrier against oxygen and moisture,” explains Galiotis. “It prevents color fading by reducing incoming harmful radiation and delaying the diffusion of oxidants.”
Galiotis and his colleagues have developed a machine to apply the veil to a painting by using atomically thin graphene grids that are vapor deposited on a copper substrate and transferred to an adhesive sheet. Two rollers gently press the painting and film together, then remove the film, leaving only the graphene layer.
The researchers exposed colored panes protected by graphene layers to a lot of light, heat and moisture – an artificial aging process. They also examined the effects on a painting – ink on glossy paper – that covered one half with its graphene veil while leaving the other unprotected. After the painting had been left in the aging chamber for over 1000 hours, the colors on the unprotected half were noticeably faded – but the colors protected by the graphene veil held.
Narayan Khandekar, director of the Straus Center for Consolation and Technical Studies at Harvard Art Museums, USA, explains that museums limit color fading by storing paintings in the dark and only exhibiting them under low-energy lights for a short time. But most paintings in private homes don’t get such treatment, he says. The idea of a protective graphene veil is “really convincing – it seems to alleviate a lot of light damage and is easy to remove. So I think it has a lot of potential. ‘ However, he notes that paintings are often protected by a layer of special resin or varnish, and researchers now need to study how these interact with the graphene veil.
Art conservation scholar Stephen Hackney, formerly of the Tate Gallery in London, UK, explains that restorers need “complete knowledge” of the materials and behavior of a painted work of art. “This is a big job, but a valid requirement that makes innovation difficult.”
Although some of the properties of the veil appear promising, “in my experience it takes a relatively long time to accept and adopt new materials and it is often the practical procedures, rather than the materials themselves, that require the most consideration”. says Hackney.