Browsing by Author "Fager, Silja"

In this study the staining of cellulose fibers with mordant dyeing and disperse dyeing techniques are investigated. Previous studies have shown disperse dyeing gives better staining results than mordant dyeing when using synthetic fibers with natural colorants. This study explores the suitability of the disperse dyeing method for cellulose fibers. The study focuses on four cellulosic fibers: viscose, bamboo viscose, lyocell and Ioncell-F. The reference fiber for testing is merino wool. All samples are knitted. There is a little research on disperse-dyed cellulosic fiber with natural colorants, but no previous research with Ioncell-F fiber at all. Disperse dyeing was tested with and without tannin mordant. Mordant-dyed samples are for comparison. Flavonoid-containing onion skins Allium cepa and anthraquinone-containing fungus Cortinarius semisanguineus were used as sources of dyes. The pH for the dye liquor was adjusted to 8 with sodium hydroxide, except for the dyebath for the merino wool that is poorly resistant to bases. Merinos dye liquor adjusted with hydrochloric acid to pH 4. Different dyeing techniques were used with the same dyebath, except for the extra batch of celluose fibres, for which a separate dyebath was prepared from the onion skins and the pH of the dyebath was kept acidic. The color values of the dyed samples were measured on a spectrophotometer, whereby the dyeing results could be viewed as L*, a* and b* values according to CIELAB. In addition, the color fastness to light and washing were tested according to the ISO standards. The dyeing results of the cellulose fibres were lower than merino wool reference in all dyeing techniques. Ioncell-F fiber dyed very similarly to the other cellulosic fibers. Onion skins gave a darker and more stable color compared to the fungus whose color was light throughout the samples and the color fastness in light and washing tests were low. According to the results of this study Cortinarius semisanguineus is poorly suited for dyeing cellulose fibers. It is preferred to dye with the onion skins with the natural pH of the dyebath, under acidic conditions by the dispersion dyeing technique. In this case, the results of the dyeing are better and more stable even without the mordant.