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UV Protection by Woolen Fabric Dyed with Natural Dyestuff

The UV protection by textiles highly depends on large number of factors such are type of fiber, fabric surface, construction, porosity, density, moisture content, type and concentration of dyestuff, fluorescent whitening agents (FWA), UV-B protective agents (UV absorbers), as well as nanoparticles, if applied. The dyes are selective absorbers. They all absorb visible light, but some absorb light in the near ultraviolet region, as well. Even though synthetic dyes are cheaper, their usage led to such consequences as carcinogenicity and some of them are toxic to the environment. Due to increased awareness of the environmental and health hazards associated with the synthesis, processing and use of synthetic dyes, most of the commercial dyers have started to re-looking to the maximum possibilities of using natural dyes for dyeing and printing of different textiles for targeting niche market. Natural dyes are usually derived from the plants, animal and mineral sources. The shades produced by natural dyes are usually soft, lustrous and soothing to the human eye, can be produced a wide range of colors by mix and match system and are usually renewable and biodegradable. However, it needs longer dyeing time and excess cost for mordants and mordanting. Applied on textiles, provide some UV blocking which depends on the structure of dye molecules, type of dye or pigment, present absorptive groups, depth of dyeing and the uniformity. According to colour physic principles, darker colors (e.g. black, navy blue and dark red) absorb UV-R much more strongly than light pastel colors. For that reason, in this chapter the UV protection by woolen fabric dyed with natural dyestuff extracted from European Ash bark (Fraxinus excelsior) and European black elderberry berries (Sambucus nigra) was researched. Since these natural dyes, as most of the natural dyes, are non-substantive and must be applied on textiles in the combination with mordants i.e. metallic salts, 4 different mordants were applied. The color parameters were measured on remission spectrophotometer. The fabric UV protection was determined according to AS/NZS 4399:1996 Sun Protective Clothing: evaluation and classification, by UV-A and UV-B transmission measurement on transmission spectrophotometer and calculation of Ultraviolet protection factor (UPF).

Wool, UV protection, natural dyestuff, Sambucus nigra, Fraxinus excelsior

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