For non-chemical engineers, a one-atom thick, invisible protective cloak that blocks oxygen may sound like science fiction—the sort of weapon a supervillain would brandish to hold earth ransom for nefarious purposes. But new research published in Nature Nanotechnology confirms that graphene, which is very real, can protect certain artworks from fading.
Graphene is a two-dimensional carbon allotrope whose molecules bind together through a phenomenon called Van der Waals forces. It is invisible to the eye but forms a honeycomb pattern under a microscope, and can be extracted from the surface of graphite using a piece of tape. Hailed as a “wonder material” since its isolation in a single-layer form in 2004, graphene has many potential uses. China appears convinced of its military and aerospace promise, and it is being used to protect roads in the U.K. Graphene is also being used for everything from filtering toxins from water to creating a “camera” to capture heart cell activity. It has also been used in paint.
“It’s super-strong and stiff, amazingly thin, almost completely transparent, extremely light, and an amazing conductor of electricity and heat,” says Costas Galiotis, a chemical engineering professor at University of Patras in Greece. “It could be likened to an invisible veil that has the ability to adhere to any clean surface.”
Galiotis—a member of the executive board of the European Union’s Graphene Flagship research initiative—and colleagues studied the museum and gallery utility of graphene, whose properties he calls “remarkable and exciting.”
Graphene offers several material advantages: it can be produced in large, thin sheets; it blocks ultraviolet light; and it is impermeable to oxygen, moisture, and other corrosive agents. Layered overtop an artwork, the researchers posited that graphene can retard irreversible color fading due to light exposure and oxidizing agents (like air). Their findings revealed graphene can prevent color fading by up to 70 percent.
The authors cite the fading of color in Vincent van Gogh’s sunflower paintings, “in which crystals of red lead have turned into white plumbonacrite due to the reaction of paint impurities with light and carbon dioxide,” as a prime example of what they hope graphene can deter.
Galiotis’s team studied graphene’s protective effect over what they say is the equivalent of 200 years of exhibition. Using both mock-ups and real, artist-donated artworks with highly light-sensitive inks, they found it seems to work best on art with smoother surfaces, such as photographs and graphic arts. For flat works, the researchers used a “roll-to-roll” technique, which they modeled on commercial laminating, but depositing graphene “veils” on rough or embossed art, including paintings with uneven brushstrokes and very fragile works, can be difficult. For those, the scholars studied a contactless approach using graphene-enhanced glass, which doesn’t touch the art and which they say can protect against fading by 40 percent better than standard museum glass without stymieing transparency. And, in contrast to commercial polymeric coatings, such as archival varnishes or spray films with UV protection, it can be removed easily.
According to Galiotis, the European art preservation community has expressed interest in this approach; however, he allows, some are reluctant to lay graphene on old paintings “due to the element of risk which is always present when you deposit even an invisible cloak onto a work of art.” Contemporary artists can lay graphene membrane upon a painting before they frame and complete the work, he says.
Another sticking point for critics—or better, unsticking point—is the researchers’ claim that removing graphene is as easy as “using a soft rubber eraser without causing any damage to the artwork,” as they write in the paper. Galiotis says he and colleagues demonstrate that erasing in this manner doesn’t affect the art beneath the graphene. This was true for graphic art and ink drawings, but erasing graphene from atop a graphite drawing would, presumably, lose the baby with the bathwater.
Chris McGlinchey, a senior research scholar at New York University Institute of Fine Arts’ conservation center, who was not involved in this paper, says it is promising that graphene can be easily erased. “However, some works of art are so fragile they can’t be cleaned that way,” he says. “I’m sure the authors are thinking about these matters if they want to see graphene used more broadly for practical use.”
Preserving art for future generations is part of conservators’ mandate, so “demonstrating as a proof of principle that graphene can prevent light-induced damage suggests it may be a useful tool in their toolkit to help accomplish that for select works of art,” he says. But he worries that graphene’s barrier against oxygen and vapor could paradoxically cause problems for some traditional art materials.
“Oil paint changes over the decades well after the artist has considered the work to be finished, and these changes produce small molecules that would normally volatilize away,” he says. “If that process is suppressed, these degradation compounds could be trapped below the graphene layer and possibly cause a foggy appearance.”
Unanticipated warping and stress may also develop. “This could happen if only one side is coated with a moisture resistant layer, and the other is left to absorb and release moisture as humidity fluctuates,” McGlinchey adds.
Graphene may find more useful applications with modern artistic media, McGlinchey says. He also thinks researchers should study whether graphene could be applied to vintage electronic media to increase its longevity.
Only time will tell whether graphene will become a standard tool in every museum conservator’s kit. A supplemental video attached to the paper shows the Mona Lisa smiling as she is treated with graphene, while her twin, who receives no such coating, frowns as she fades over time.
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