Graphical Abstract from *‘Visualising varnish removal for conservation of paintings by fluorescence lifetime imaging (FLIM)’* on Heritage Science.

In the world of art conservation, a groundbreaking development has emerged that promises to transform the way we approach the restoration of historic paintings. A team of researchers, in 2023, from King's College London and the University of Edinburgh has developed a novel technology that harnesses the power of fluorescence to remove the guesswork from painting conservation. This innovative approach, utilizing macroscopic fluorescence lifetime imaging (FLIM), offers unprecedented accuracy in identifying and removing old varnish from paintings, potentially revolutionizing the field of art restoration.

The Research

At the heart of this breakthrough is a highly sensitive camera and imaging software developed by a team led by Professor Klaus Suhling and Dr. Jakub Nedbal from the Department of Physics at King's College London. Their findings, published in Heritage Science, detail the creation of a 25,000-pixel camera that employs a technique called macroscopic fluorescence lifetime imaging (FLIM). This marks the first time FLIM has been applied in the realm of art conservation.

*Varnish removal imaged by UV, visible light, and average fluorescence lifetime contrast.* Image from Heritage Science.

The camera works by harnessing the natural fluorescence of centuries-old varnish. When exposed to blue light, the varnish fluoresces, and the camera's pixels, each equipped with a "stopwatch," measure the time it takes for this fluorescent light to enter them. By comparing the fluorescence timing of the varnish against other components in the painting, such as paint, binders, and canvas, the researchers can create a highly accurate map of where varnish residue remains on the painting's surface.

Professor Suhling explains, "Our method is an entirely new approach. The camera has a stopwatch in every pixel that tells you when the light from a surface enters it. We can shine a blue light against a painting, and then use the camera to time how long it takes the act of varnish fluorescing to enter these light-sensitive pixels against other components in the painting."

This level of precision is unprecedented in the field of art conservation. Traditional methods of varnish removal have relied on conservators using UV lamps to visually identify varnish residue, a process that is highly subjective and prone to inaccuracies. The new FLIM technology eliminates the need for guesswork, providing conservators with detailed imaging that allows for a new level of confidence and accuracy in their work.

The Technology Behind the Discovery

The FLIM technology developed by the researchers is a fascinating blend of different scientific disciplines. At its core, the technique borrows from the medical field, where fluorescence is commonly used to study, track, and identify cancerous cells. However, the researchers have taken this concept further by incorporating light-sensitive technology pioneered in astronomy.

The result is a camera that can provide a clearer contrast of varnish imaging than that afforded by handheld UV lamps. This interdisciplinary approach showcases the potential for innovation when different scientific fields collaborate and share knowledge.

The camera itself is a marvel of engineering. With 25,000 pixels, each containing its own "stopwatch," it can capture an incredible amount of detail. The use of blue light for excitation is also significant, as it minimizes potential damage to the artwork compared to more energetic UV light often used in traditional conservation methods.

Implications for Art Conservation

The implications of this discovery for the field of art conservation are profound. Professor Aviva Burnstock from The Courtauld, who was involved in the research, states, "This technique has provided more detailed information about the paint and varnish during removal tests than any other previous method, paving the way for whole painting imaging during varnish removal. If achieved, that would be a great advance for painting conservators."

The ability to accurately map varnish residue on a painting's surface allows conservators to approach the restoration process with unprecedented precision. This could lead to several significant improvements in art conservation:

Minimized Risk to Artwork: By clearly identifying areas of varnish residue, conservators can avoid over-cleaning or accidentally removing original paint layers, thus minimizing the risk of damage to priceless artworks.
Improved Conservation Outcomes: The increased accuracy in varnish removal could result in more faithful restorations, bringing paintings closer to their original appearance without compromising their integrity.
Time and Resource Efficiency: While the initial setup of the FLIM technology may be time-consuming, its precision could ultimately save time and resources in the long run by reducing the need for repeated treatments or corrections.
Standardization of Conservation Practices: The objective data provided by FLIM could lead to more standardized practices in art conservation, reducing variability between different conservators and institutions.
New Insights into Painting Techniques: The detailed imaging provided by FLIM might offer new insights into historical painting techniques and materials, contributing to our understanding of art history.

Potential Challenges and Future Directions

While the development of FLIM for art conservation is undoubtedly exciting, it's important to consider potential challenges and areas for future research:

Cost and Accessibility: The sophisticated technology behind FLIM may be expensive, potentially limiting its accessibility to smaller museums or conservation studios. Future research might focus on developing more cost-effective versions of the technology.
Training and Implementation: Adopting this new technology will require training for conservators. Developing comprehensive training programs and best practices for using FLIM in conservation will be crucial.
Application to Different Types of Artwork: While the current research focused on easel paintings, future studies could explore the application of FLIM to other types of artwork, such as sculptures or frescoes.
Long-term Effects: As with any new conservation technique, long-term studies will be necessary to ensure that the use of FLIM and the associated blue light exposure doesn't have any unforeseen effects on artworks over time.

Exploring the integration of FLIM with other conservation technologies and techniques holds promise for developing more comprehensive approaches to art restoration. By combining FLIM's capabilities with complementary methods, conservators could gain a more holistic understanding of artwork condition and make more informed decisions about preservation strategies. This synergistic approach may enhance the overall effectiveness of conservation efforts and potentially open new avenues for protecting and restoring cultural heritage.

The Need for Open Discussion of New Discoveries

As an observer of this field (for now), it's striking to note that despite the potential significance of this discovery, there has been relatively little discussion about it in the wider scientific and art conservation communities. Besides the original research paper and a single article from King's College London, information about this breakthrough has been scarce. This lack of widespread discussion highlights a broader issue in scientific research and innovation: the need for more open and accessible dialogue about new discoveries. While specialized journals play a crucial role in disseminating research findings, there's a clear need for more platforms and opportunities to discuss these discoveries in a way that reaches a broader audience.

Several factors could contribute to this phenomenon. First, research often remains confined within specific academic disciplines, making it challenging for interdisciplinary discoveries to gain widespread attention. These academic silos can prevent the cross-pollination of ideas and limit the potential impact of groundbreaking research. Secondly, there's a pressing need for more effective science communication to bridge the gap between specialized research and public understanding. Many researchers lack the training or resources to effectively communicate their findings to a non-specialist audience, leading to important discoveries being overlooked or misunderstood.

Another factor to consider is the slow adoption of new technologies in fields like art conservation. This caution is understandable given the irreplaceable nature of many artworks, but it can also hinder progress and prevent potentially beneficial technologies from being implemented. Additionally, limited funding for art conservation research may result in fewer resources being dedicated to publicizing and discussing new discoveries, further contributing to the lack of widespread awareness.

Conclusion

The development of macroscopic fluorescence lifetime imaging for art conservation represents a significant leap forward in the field. By providing unprecedented accuracy in identifying varnish residue, this technology has the potential to transform the way we approach the restoration of priceless artworks.

However, the limited discussion of this discovery outside of specialized circles highlights a broader issue in how we communicate and engage with new scientific breakthroughs. As we continue to push the boundaries of what's possible in fields like art conservation, it's crucial that we also find ways to foster more open, accessible, and widespread discussion of these discoveries.

By doing so, we can not only accelerate the adoption of beneficial new technologies but also inspire the next generation of researchers and conservators. The story of FLIM in art conservation is not just about preserving our cultural heritage—it's about the importance of sharing knowledge and fostering innovation across disciplines. As we move forward, let us strive to create an environment where groundbreaking discoveries like this receive the attention and discussion they deserve, ultimately benefiting both the scientific community and society as a whole.

Illuminating the Past: How Fluorescence is Revolutionizing Art Restoration