Credit: © 2009 Wiley

Stable nanodroplets form in microemulsions when two immiscible phases such as oil and water are mixed together in the presence of a surfactant. Many different types of microemulsions exist and they have been used in various cleaning applications. Researchers at the University of Florence now report that nanodroplets in oil-in-water emulsions when embedded in a polymer network can become effective cleaning agents for different pieces of art, including paintings and gilded surfaces.

To preserve the structure and performance of the microemulsion system, Piero Baglioni and colleagues1 embedded a previously studied p-xylene-in-water microemulsion into a hydrophobic hydroxyethylcellulose polymer network with the aim of using the mesh size and viscosity of the network to control the diffusion of the nanodroplets; cleaning agents that are more viscous will penetrate less into the porous matrices of paintings. Small angle X-ray scattering and differential scanning calorimetry experiments confirmed that the structure of the embedded nanodroplets, which was essential for the cleaning process, was retained. The aged protective coating on a fifteenth-century painting and an eighteenth-century gilded frame was successfully removed using the material.

Such water-based cleaning agents offer a simple and less invasive way of cleaning works of art because these systems are optically transparent and cleaning can be visually monitored.