Physico-chemical characterization of innovative natural materials for the consolidation of aged flax fibres

Canvas has begun the favourite painting’s support of the modern age. Flax has been the natural fibre mainly used for this purpose in the centuries. One of the main conservative problem that affects natural fibres is the depolymerisation of cellulose chains. This process involves a decrease of the molecular weight of cellulose chains, that results in a drastic fall of the mechanical resistance of the fibre cell, of the yarn and the fabric as a whole. The restoration procedure more used in the centuries to overlap the structural failure of painting supports, due to depolymerisation and degradation of fibres, is the lining technique. However it represents a controversial method because of the irreversible modifications of the original painting matter that involves, due to the high temperature and pressure conditions requested by the procedure. The aim of this project was finding a material able to consolidate and restructure fibres, actually improving the mechanical characteristics of the old flax canvas and archaeological textiles, which could represent an alternative to line, at least in the less damaged cases. To reach this goal two different products has been tested as consolidant materials: Funori, an heterogeneous mixture extracted from a family of Japanese red seaweeds; a cellulose derivative synthesized by the research group of Prof. Antonella Salvini, associated professor of the “Ugo Schiff” Chemistry Department at the University of Florence; Both the products chosen for the experimentation are characterized by a similar chemical nature with the flax fibre composing canvas supports. This characteristic not only guarantees the chemical compatibility of the two consolidants with the support they will be applied on, but it also allows to suppose the establishment of chemical interactions between the products and the support. Moreover, the combined treatment with calcium hydroxide nanoparticles dispersions has been tested. The aim was to add the preservative action of alkaline earth metal hydroxide nanoparticles against acidic hydrolysis of cellulose to the consolidating action of the two products chosen for the experiment.