Vliv barvení železo-galovým komplexem na degradaci lnĕné tkaniny / The impact of dying by iron-gallic complex on the degradation of linen fabric

The aim of this study was to identify the impact of ferrous pickle, iron gall ink and the dying process on the degradation of linen fabric. Similarly to paper conservators dealing with the problem of corrosive impact of iron gall ink on paper, an analogous issue is being handled for fabric dyed black or brown. It is caused by the same materials used for dying and making of ink (melanterite (FeSO₄·7H₂O) and oak galls and tree bark as a source of tannin) and the same building element of paper and fabric of a vegetable origin (cellulose). In contrast to papers written on with ink, dyed fabric was rinsed in water many times during the dying process, therefore the substances associated with the formation of iron gall complex that may affect degradation of the cellulose bearer could be sufficiently washed away. And it is the process of dyed fabric multiple rinsing that may be the reason of why black and brown dyed fabric is still in good shape compared to papers written on with iron gall ink. In spite of that it is reported that black and brown dyed fabric is often in a bad shape. The damage of fabric was determined by measuring an average polymerization degree of cellulose, cellulose copper number, solubility in alkaline scour and pH of the aqueous extract. The results indicate that despite having been rinsed in water several times during the dying process, the fabric still contained substances accelerating degradation. The negative impact of iron ions (pickle) was partly eliminated after their complexation with the dye.