A nanofluid system to restore wall paintings has been developed by Italian scientists. The mechanism could help develop tailored solutions for artwork conservation. 

In the past, art conservators tried to protect wall paintings using synthetic organic polymer coatings. Unfortunately, these coatings are now known to damage the paintings when they degrade, making their removal a priority in art conservation. Scientists have developed water-based micro-emulsions (nanosize oil droplets in a water medium) that are more effective in removing the polymers without damaging the paintings than traditionally used neat organic solvents. 

Now Piero Baglioni and colleagues at the University of Florence in Italy, have developed a novel nanofluid formulation and investigated the cleaning mechanism on Mesoamerican wall paintings in Mexico. Their system uses a formulation of sodium dodecylsulfate, pentanol, ethyl acetate and propylene carbonate (EAPC) in water to form a micellar system of nanosize spheres. 

When applied to the painting, the polymer coating absorbs the solvent mixture causing it to swell and detach form the painting's surface. The nanocompartmentalised structure of the EAPC system allows the polymer to choose the mixture of solvents that it absorbs itself, according to its own physical and chemical properties, explains Baglioni. This means that this cleaning system has the potential to deliver the optimum solvent mixture for removal of any polymer. 

By deciphering this mechanism, the group has opened a new world of possibilities for art conservation: 'we have developed and studied nanostructured systems for polymer removal before; now it is time to deeply understand why these systems are so effective so we can predict the efficacy of a cleaning system by knowing its composition and the polymer to be removed', says Baglioni. 

Paolo Samorì, an expert in nanochemistry from the University of Strasbourg in France, comments, 'this is a bright example of how nanoscience can be used effectively to solve a wide variety of open issues, even in unexpected applications such as the removal of harmful polymer coatings from the surface of works of art.'

'Conservation science is a relatively young subject,' Baglioni concludes, but 'the contribution that chemistry, physics and nanosciences in general can give to art conservation is huge'. 

Amaya Camara-Campos 

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