Essential oils represent a good alternative to chemical biocides as they have antiseptic, antibacterial and antifungal properties, inhibiting the formation and proliferation of biofilms which can occur on outdoor and indoor surfaces of ancient and modern artworks. In this review, we illustrate how their antimicrobial properties, known since antiquity in phytotherapy, have been studied and tested for conservation purposes since the 1970s. In vitro tests on a wide range of plant extracts and in situ applications of specific volatile compounds have shown selective antibacterial and antifungal properties after the individual action of pure components or as the synergic effects of pre-determined mixtures. The review emphasizes the broad spectrum of materials—organic and inorganic—that essential oils can be applied to as biocides and finally emphasizes how the demand for commercial solutions has rapidly grown in bioconservation. The review demonstrates how research on the subject has been powerfully boosted by the ecofriendly and harmless character of essential oil applications, which makes them one of the most sustainable options in heritage conservation nowadays. The review elucidates how research is developing novel solutions for the application of EO blends—like encapsulation and microemulsions—and their optimization in commercial products for heritage conservation.

Spectrally-resolved imaging provides a spectrum for each pixel of an image that, in the mid-infrared, can enable its chemical composition to be mapped by exploiting the correlation between spectroscopic features and specific molecular groups. The compatibility of Fourier-transform interferometry with full-field imaging makes it the spectroscopic method of choice, but Nyquist-limited fringe sampling restricts the increments of the interferometer arm length to no more than a few microns, making the acquisition time-consuming. Here, we demonstrate a compressive hyperspectral imaging strategy that combines non-uniform sampling and a smoothness-promoting prior to acquire data at 15% of the Nyquist rate, providing a significant acquisition-rate improvement over state-of-the-art techniques. By illuminating test objects with a sequence of suitably designed light spectra, we demonstrate compressive hyperspectral imaging across the 700–1400 cm^-1 region in transmission mode. A post-processing analysis of the resulting hyperspectral images shows the potential of the method for efficient non-destructive classification of different materials on painted cultural heritage.

The pigments used by artists since ancient times play an important role in historical, artistic, and cultural investigations. They allow the acquisition of useful information for the study of human and technological development. This research aims at differentiating the various sources of azurite exploited in antiquity, based on the study of minor and trace elements. Azurite is one of the most important blue pigments in art history, widely used during the Middle Age and Renaissance. However, very few studies investigated the provenance of the pigment, so today it is still not possible to clearly identify the sources of azurite exploited in the past. This study is based on the analysis of several samples of azurite belonging to the MUST collection (Museum of Earth Sciences, Sapienza University of Rome, Italy) and coming from different historical localities: UK, Italy, Germany, France, Romania and Slovakia (both representative of the resources within the ancient Kingdom of Hungary), Greece and Russia. The samples were analysed by electron microscopy (EMPA and SEM-EDX) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), with the aim of detecting chemical features that are specific to the different azurite ore deposits.