الفهرس 
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Abstract
Recently, there has been a growing interest in the use of natural dyes in textile applications. Natural dyes can exhibit better biodegradability and generally have a higher compatibility with the environment. Also, they can show a lower toxicity and allergic reaction than synthetic dyes.
Natural dyes are generally understood to be colourants (dyes or pigments) that are obtained from animal or vegetable matter without chemical processing.
Natural dyes, with a very few exceptions are non substantive, but required to be used in conjunction with mordants. The only problem of the use of mordants with natural dyes is that, whilst the dyes are themselves, generally harmless, the chemicals used for mordanting or fixing the dyes are generally not environ-mentally acceptable.
Chromium (potassium dichromate), copper (copper sulphate), alum (aluminium potassium sulphate), and iron (ferrous sulphate) are the most effective and the main chemicals used for mordanting natural dyes.
Out of these salts, according to eco-standards, the copper and chrome are red listed. Both of them are potentially harmful to the environment leaving a substantial proportion of mordant unexhausted in the spent mordant bath and thus may pose serious effluent problems.
Taking into account, the metal contaminants left in the spent mordant bath, and their effect on the environment, a systematic study on premordanting wool, silk and cotton fabrics with K2Cr2O7 and CuSO4, has been done for cleaner mordants.
Premordanted fabrics were then dyed with aqueous extract of natural dye Henna containing lawsone as the main colourant species. Furthermore, the utilization of 2-hydroxy-1,4-naphthoquinone (Lawsone) and some of its synthesized derivatives in dyeing premordanted wool, silk and cotton fabrics, was also established.
The dyeing behaviour has been assessed by measuring the colour strength (K/S) values and different fastness properties of the dyed fabrics.