What would happen if someone let a gecko lizard walk across the Mona Lisa? Probably nothing. The gecko would simply make its way across the painting, and on to some other masterpiece. However, if someone tried to pull the poor lizard away from the picture, it would probably ruin the paint layer beneath. Why is this the case?
Geckos are a group of over one thousand lizard species, 60% of which can walk on virtually any surface and without worrying whether that surface is vertical or even upside down. This is due to their unique ability to stick their feet to almost anything and detach them within milliseconds. Geckos can do this because they have nanosized structures on their feet – microscale hairs, called setae, which branch into even smaller, nanosized hairs with spatula-shaped tips called spatulae. The gecko’s trick is hidden in the extremely small size of these tips, which allows them to closely adhere to any unevenness in the surface. Indeed, they can get so close that they bond to it with van der Waals forces.
For example, in Tokay Geckos, their astonishing one billion spatulae provide an overall adhesion exceeding a hundred times the gecko’s own weight. And yet the lizard is still able to walk really fast. This is thanks to its ability to roll back its fingers, which breaks the connection one nanohair after another, hence it needs only a small fraction of the adhesion force to actually detach its foot from the ground.
Since the discovery of the phenomenon of gecko adhesion, scientists engineering new materials have tried to mimic the behaviour of gecko pads with the aim of creating a gecko-inspired dry adhesive (GDA). Among the most popular materials used to make GDAs are siloxanes and silicones, as well as polyurethane and polyethylene, which are usually etched or moulded into the form of a gecko-like surface.
Art conservators have a set of guiding ethical principles when treating an artwork. Among them, two are especially crucial. The first requires a conservator to limit his or her action to a minimum, in order not to alter the original matter of the artwork too much. The second tells the conservator to use, as far as possible, materials and techniques that could be reversed in the future. In terms of adhesives, both of these postulates are difficult to fulfil.
Adhesives react with objects chemically and sometimes physically, thereby permanently altering them. GDAs might replace adhesives now used in some conservation procedures, thanks to their exceptionally good adhesion in a perpendicular direction and in a parallel direction to the surface, as well as allowing easy detachment when peeling them off, making them a great alternative to traditional adhesives.
I am trying to determine the preliminary entry conditions for the use of GDAs in art conservation. I asses the potential effectiveness of using GDAs in different situations and their safety. I measure how different GDAs adhere to materials observe how much force is needed to detach the GDA and what damage it might cause to artworks. If this research confirms the theoretical premises, we might face a shift in current conservation procedures, especially in the mounting and transportation of artworks and archaeological artefacts, making it easier for Mona Lisa to travel and keep her smile for longer.
About the Author
Jacek Olender: I hold an MA in art conservation and a BA in philosophy from Nicolaus Copernicus University in Torun. Currently, I study at the PhD programme at the Courtauld Institute of Art in London, where I conduct my research on gecko-inspired dry adhesives for art conservation. I am also affiliated as a philosopher with the Institute of Philosophy and Sociology of the Polish Academy of Sciences, where I study methodology of science and scientific institutions. I am passionate about art and I try to combine both my backgrounds and treat science as one great humanity endeavour.