Our results show -counter-intuitively- that fibres extracted from the paintings dated a few hundred years ago have undergone more marked changes than the thousands-year-old fibres from Egypt.

A general stiffening was found in almost all the ancient fibres compared to a modern reference linen thread, but the threads in the paintings also showed structural changes, not only in the structural defects already identified as weak points by the study of the Egyptian threads, but also due to other issues of oxidation or hydrolysis, or fungal attack.

Despite the effects of ageing, two-photon microscopy showed good stability in the organisation of cellulose, a molecule of which flax is composed of 80%. Solid state NMR and infrared spectroscopy provided additional information on changes in the biochemistry and structure of the fibres.

These findings provide insights on the ageing of modern flax, which are used, for example, in the design of composite materials for the automotive, nautical and aeronautical industries. Based on the strength pf these results that could impact various disciplines, a new project called ANUBIS has been launched, financed by the French National Research Agency (ANR, topic Bioeconomy).