Investigation of flax yarns from italian paintings using AFM mechanical characterization

International audiencePrevious studies have shown the interest in using Atomic Force Microscopy (AFM) to investigate the parietal mechanicalproperties of hemp or flax fibres, in correlation with their structure or maturity (1–3), especially in PeakForce QuantitativeNanomechanical Property Mapping (PF-QNM) mode. However, this technique is relatively new, and its application is oftenlimited to the engineering and biological fields, but the small quantity of the sample required make it a useful tool also to studymaterials from the cultural heritage. In this research, two yarns of few centimetres were taken from the back of four Italianpaintings of the art gallery of Ascoli Piceno, dated around 1600-1700, and one yarn of each pair was selected for the AFMmechanical characterization. PF-QNM analysis was performed with a Multimode AFM (Bruker Corporation, USA) equipped witha RTESPA-525 probe (Bruker Corporation, USA) and a maximum load of 200 nN; the cantilever was carefully calibrated using theSader method and the indentation modulus of Highly Oriented Pyrolytic Graphite (HOPG) was taken as reference