Viscose rayon: an absorbing problem. An investigation into the impact conservation wet cleaning treatments have on historic woven viscose rayon fabrics; with a supplementary analysis of current techniques for identifying man made fibres

Abstract

Poor wet properties are attributed to viscose. Research has shown how the fibre’s manufacture influences this characteristic and how progressive improvements to processing methods mean that viscose rayons pre-1940 have even poorer wet properties than later versions. It was decided to investigate the implications this has for conservation wet cleaning treatments. Tensile strength testing was carried out on specimens of viscose rayon from three eras – c.1940s, c.1960s and c.1980/90s – which had been subjected to a wet cleaning treatment, to contextualise research for conservation. Both Orvus WA® and Dehypon LS45 were used for wet cleaning. Results showed the two later viscose rayons lost significant strength in the wet state, up to 50%. The c.1940s fabric had a greater strength reduction of around 80% - however, degradation from a black colourant present was shown to have affected results. This highlighted the risk that degradation, even if not visible macroscopically, can be significantly exacerbated in viscose rayon when wetted. It was concluded that wet cleaning viscose rayon can be a suitable with either the aforementioned detergents, although it may be less appropriate for older more degraded versions. Problems with the fibre identification of viscose rayon were also explored, showing successes in using a combination of different basic analytical techniques.