Polycotton Canvases, Characterisation, and Mechanical Behaviour Before and After Artificial Ageing

In recent decades, polycotton canvases, which are made with mixtures of cotton and synthetic fibres, have appeared on the market and are used by artists. The aim of this article is to identify, characterise, and evaluate the mechanical behaviour before and after an ageing process of three representative types of polycotton canvases, and to compare them with the more traditional and studied linen canvases. The characterisation results provide information on the proportion of fibres in the three polycottons studied, as well as new technologies in the spinning and sizing of their yarns. A new measurement system that improves the accuracy of measuring the effective cross-sectional area of the canvas has been developed. The dynamometric and bursting tests results allow us to quantify the lower resistance of polycotton canvases compared to traditional linen. Additionally, they reveal some peculiarities such as a greater stiffness of the warp compared to the weft threads in polycotton canvases. This is opposite to what occurs in linen canvases. The differences between warp and weft threads in polycotton canvases, along with the use of the open-end spinning system, provide valuable information for proper conservation and future restoration interventions. Additionally, the open-end spinning system involves a greater water absorption capacity compared to ring yarn fabrics.