Studying old paintings helps us to understand the ageing of the eco-materials of the future

Flax fibre is of great interest to manufacturers because it is more environmentally friendly than plastic. How does this fibre age over time? There are two ways of finding out how a material stands up to the passage of time: either you have to age it artificially in the laboratory, using temperature, humidity and a few mechanical manipulations, or you have to analyse objects that are several centuries old. That's why a Franco-Italian team (involving the CNRS and INRAE, the French research institute for agriculture and the environment) went out and took a few square centimetres of flax fibre from Italian paintings dating from the 17th and 18th centuries - they took the sample from the back of the painting so it wouldn't show - and analysed it using the latest microscopes and infrared spectroscopy. They had already done the same thing a few months ago, analysing 4,000-year-old Egyptian mortuary textiles. The result: the images show, on a nanometric scale, that linen fibres are highly resistant to the passage of time.

To the great surprise of researchers, Egyptian linen fibres are even better preserved than those found in Italian paintings (which have been subjected to the chemical action of paint and sometimes to unfortunate restorations). But in both cases, flax fibres may stiffen a little, but they retain their solidity, which validates their use in the manufacture of more environmentally-friendly materials in industry. This includes replacing fibreglass in parts for the automotive and aerospace industries.

Studies to be carried out on hemp

Other ancient plant fibres could be rediscovered and brought back into fashion. After flax, researchers would like to study the ageing of hemp fibres, which also have a bright future in terms of eco-design. Hemp has the advantage of growing easily here without consuming too much water,’ explains Johnny Beaugrand, a biochemist at INRAE, one of the authors of the study. To find out more about how they age, the idea now would be to look at old ships to study samples from the past. Hemp has been used for centuries for ropes and sails.