Applications of graphene nanoparticles can strengthen materials, resist fungal growth, and block the harmful effects of light and moisture in art and artifacts.

Even as contemporary art materials develop more archival and colorfast formulations, common environmental factors of light and moisture are unavoidable. Airborne chemical agents and the inevitable hazards of subtle wear and tear are the constant companions of archivists and restorers who look after the world's heritage sites and masterworks.

Several oil-based paintings, from Georgia O'Keeffe's paintings housed in Santa Fe, New Mexico, to Van Gogh's Sunflower series and works by Rembrandt, have been fading over the last century due to constant exposure to light. Chromium in the yellow Van Gogh favored has reacted strongly with other compounds like barium and sulfur when exposed to sunlight, and research has demonstrated that sulfates in various ancient pigments, which absorb in the ultraviolet (UV) spectrum, have suffered blistering and degradation.

Even shut away from the pigment-fading light and temperature changes of public display, fungal attacks and degradation through airborne exposure to volatile organic compounds (VOCs) can lead to corrosion, oxidation, yellowing, and fading.

"However, recent advancements have led to the emergence of minimally invasive techniques that prioritize authenticity while effectively mitigating deterioration. Nanotechnology, for example, has opened new possibilities for the consolidation and protection of cultural heritage materials, offering enhanced durability without compromising aesthetic value," wrote Lucía Pérez-Gandarillas and co-authors in a research paper covering the insights and trends of modern methods of art preservation.

"To minimize its deterioration, cultural heritage has traditionally undergone diverse preservation and maintenance treatments, and the attention of researchers to developing new and innovative methods for state diagnosis and protection treatments has been increasing in the recent decades," the paper stated. "The findings show an increasing number of studies in this field in the last decades, particularly since 2010. Italy, home to the largest number of UNESCO heritage sites, is the most prolific country. Most of the studies are related to metal, paper, and stone as substrates to be protected. Significant progress has been made in understanding the deterioration processes through precise diagnosis and the development of innovative treatments for protection. In this sense, the latest trends have been detected, such as the use of non-invasive techniques for diagnosis and the use of nanotechnology and nature-based treatments for conservation treatments."

Protecting old and new works

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Graphene is composed of a single layer of carbon atoms arranged in a hexagonal lattice. That structure gives it many unusual properties that hold great promise for real-world applications: batteries, supercapacitors, antennas, water filters, transistors, solar cells, touchscreens, and now art preservation.

Other alternatives to traditional formulations and treatments are based on graphene and graphene-related materials (GRMS), whose unique properties make them excellent candidates for protective performance, including anti-corrosion, UV-aging resistance, and impermeability.

Apart from GRMS, other 2D innovative materials are being investigated for the protection of newly produced dyes and inks, like tungsten disulfide, molybdenum disulfide, and hexagonal boron nitride, which are known to absorb UV light as promising candidates for colorfastness to endow paints used both in art and architecture with eco-friendly, lightfast, anti-fading properties and durability.

To combat the steady onslaught of time, there has been extensive study on the use of nanomaterials for conservation of existing artworks. Graphene, while gaining in popularity across the fields of medicine and new materials, has several properties that make it attractive for art conservation as well.

The one-atom-thick material is transparent, adheres easily to various substrates, and serves as an excellent barrier against oxygen, corrosive gases, UV light, and moisture – the great enemies of art preservationists.

Researchers have leaped on the inherent qualities of graphene as a protective agent: "Graphene can be produced in thin large sheets, blocks ultraviolet light, and is impermeable to oxygen, moisture and corrosive agents; therefore, it has the potential to be used as a transparent layer for the protection of art objects in museums, during storage and transportation," an article in Nature Nanotechnology revealed, where research has demonstrated that a graphene veil, produced by vapor deposition, can be layered onto artworks to shield against color fading, with a demonstrated protection factor of up to 70%.

"Overall, the present results are a proof of concept of the potential use of graphene as an effective and removable protective advanced material to prevent colour fading in artworks."

The process is also reversible. The molecule-thin protective layer can be removed using a soft rubber eraser without causing any damage to the artwork. The study also explored a contactless deposition of graphene on picture-framing glass for use when the direct application of graphene is not feasible due to surface roughness or fragility.

A passive guardian

Graphene-based aerogels have been increasingly used as superior absorbers of toxic pollutants, proving to be highly effective in VOC absorption thanks to their unique structure and high surface area.

Graphene and transition-metal dichalcogenides (layered compounds of two elements) of molybdenum disulfide and tungsten disulfide were combined to create three-dimensional aerogels that absorb certain harmful substances – the macrostructures led to the selective absorption of ammonia, and with the addition of the ionic liquid 1-hexadecyl-3-methylimidazolium chloride promoted higher rates of VOCs absorption and anti-fungal activity.

In simpler terms, scientists combined thin layers of molybdenum disulfide and tungsten disulfide with graphene to make a super light, sponge-like structure. This "sponge" can soak up harmful gases, especially ammonia.

Adding a special liquid (called an ionic liquid) makes it even better at trapping other toxic chemicals and also helps prevent mold. So, this new material could be useful for cleaning the air and keeping surfaces free of fungus.

These layered materials did a better job than regular sponges at soaking up harmful chemicals like ammonia, formic acid, acetic acid, formaldehyde, and acetaldehyde, making them useful for protecting artwork and artifacts in places like museums, galleries, and archives.

"Tackling the degradation of cultural heritage requires a global effort. We call on all material scientists to develop new nanomaterials and methods for the preservation of artwork," wrote the authors of Nanomaterials in art conservation, Piero Baglioni, Emiliano Carretti and David Chelazzi.

Fragile historical treasures and works of art are only getting older, and their future security rests in the hands of scientists as much as their fellow researchers and art custodians.