Controversial influence of aqueous treatments on historic textiles

Different historic textiles were subject to aqueous treatments with and without sodium borohydride as a reducing agent. As the action of borohydride generates an alkaline environment that is potentially harmful for oxidized cellulose in historic textiles, two less alkaline treatment options using buffer systems were additionally tested.In order to track the impact of the treatments on the samples, the development of oxidized cellulose functionalities and of the molecular weight was analyzed by selective labelling of carbonyl and carboxyl groups combined with gel permeation chromatography and multi-detector set-up. The crystallinity index of the samples was analyzed by CP-MAS NMR to elucidate the impact of age and treatment on the historic material.Already pure aqueous treatment changed the molecular weight distribution of historic textiles in some cases. These changes are discussed in the context of oxidized cellulose functionalities and crystallinity index. Furthermore the chosen historic samples reacted best towards a reduction treatment with sodium borohydride that had not been buffered, whereas the two buffered systems caused more damage and failed to reduce carbonyl groups along the cellulose chain.