At the present time the employment of natural products and the research of eco-friendly solutions is mandatory in all the fields of research. The restoration of cultural heritages employed chemical products for many years following the imperative of the conservation, but today new approaches and solutions can be found. Essential oils can be one of the successful solutions in preventing degradation of different materials. The biocidal efficacy of three of them: Calamintha nepeta, Origanum vulgare and Thymus vulgaris and their respective major components (pulegone, carvacrol, thymol) has been already assessed against different microorganisms colonizers of stone materials.
Wood is one of the main components of cultural heritage. Thanks to the great availability, the relative low cost and the incredible versatility it has been used for an incredible number of different applications: carpentry, furniture production, paintings support, sculptures and musical instruments. As others, and probably more than others natural products, wood can be affected by important phenomena that required specific hydro-climatic parameters and a constant maintenance to prevent or slackening degradation.
The aim of this project is to have a systematic evaluation of the efficacy of the aforementioned phytochemical compounds in the reducing and preventing biological attack on wood.
The effect of phytochemical compounds, in different concentrations and compositions, on different species of wood will be assessed. Morphological, physical and colorimetric characterization of the samples and the determination of their specific bioreceptivity will be evaluated. Moreover, to better investigate the behavior and eventual changes of the physical properties of the wood samples in presence of the biofilm and the phytochemical compounds, NMR technology will be employed in an innovative way.
The employment of eco-friendly substances for the treatment of biodegraded artefacts would represent an important progress in the field of chemical research applied to the conservation of cultural heritage, where the theme of eco-sustainability is becoming increasingly important. In recent years the chemical products employed in this field were targeted mainly on the resolution of the problems that affect the work of art, not considering possible secondary effects on human health (restorers and visitors) and on the surrounding environment. The selected essential oils are natural products normally used in everyday life and their toxicity, in the employed concentrations, is considerably lower than the one of classical biocidal products. However, even if the biological activity and the eco-sustainability of essential oils is well known, little is being said about their high costs and the impossibility of controlling their chemical composition. For these reasons, this research proposes a possible alternative that provides the employment of the major components of the selected essential oils, mixed together in the appropriate concentrations, to provide a better control in the elimination of the microorganisms.
Another innovative aspect concerns the application of the products on wood remains. The related bibliography is very scarce [17] [18] [25] but the results are very promising. Many different essential oils are available and only some of them have been tested. It is now important the experimentation of a wide range of different essential oils in order to assess which ones are the best in the conservation of wood depending on the morphological characteristics of the object and also the kind of attack.
All the methodologies that will be used are non-invasive and non-destructive, in keep with the basic principles of the diagnostics on cultural heritage. Among these methodologies, the unilateral portable NMR stands as an innovative advanced application of the classical nuclear magnetic resonance and is particularly suitable for the monitoring of the conservation status of non-transportable artistic artefacts, that will be employed for the first time in this kind of study.
[17] P.C. Wu and C.L. Chou, "Utilisation of essential oils for wooden sculpture conservation at Juming Museum", Journal of the Institute of Conservation, vol. 41, no. 3, pp. 235-245, 2018.
[18] F. Palla, m. Bruno, F. Mercurio, A. Tantillo and V. Rotolo "Essential Oils as Natural Biocides in Conservation of Cultural Heritage", Molecules, vol. 25, no. 3, 730, 2020.
[25] M. Bahmani and O. Schmidt, "Plant essential oils for environment-friendly protection of wood objects against fungi", Maderas. Ciencia y tecnología, vol. 20, no. 3, pp. 325-332, 2018.