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Introduction
As is well known, synthetic dyes offer a wide range of colours, good fastness and moderate cost and for these reasons, they have replaced natural dyes in recent decades ([1] Bechtold et al. , 2006). However, with the realisation of the toxicity and polluting effects of synthetic dyes, there is a growing interest in the use of natural dyes in textile dyeing ([2] Bechtold et al. , 2003). Natural dyes are friendlier to the environment than synthetic dyes, can exhibit better biodegradability, and generally have a higher compatibility with the environment ([9] Tsatsaroni and Liakopoulou-Kyriakides, 1995; [8] Nagia and El-Mohamedy, 2006). Natural dyes from plant material such as berberine ([5] Kim et al. , 2004), mulberry fruit ([10] Tu and Wang, 2004) and carthanin ([12] Xu, 2004) have been recently investigated. However, natural dyes from food industry by-products have not been used to dye textiles by far.
In China, the chestnut resource is very abundant, constituting 60 per cent of the world yields ([11] Wu et al. , 2007). Chestnut shells are the waste product from chestnut food processing and have not been fully utilised to date.
The glace chestnut industry produces each year a huge amount of chestnut shells as waste, reuse of which would help solve the pollution problems caused by their disposal ([4] Gomez et al. , 2005). These shells contain a large quantity of brown pigment which is mainly used in the food industry, where it is gradually replacing caramel pigment, although with some toxicity at high concentrations. To the authors' knowledge, PBFCS has not yet been used as a natural dye for textiles.
Flax is an abundant and widely used fibre plant with wide distribution in many counties. Flax fibre is a reproducible biomaterial and has the properties of high tensile strength, fineness and water absorption. Flax fabric has good hygroscopicity and air permeability which give it a comfortable feel. However, the cellulose in flax fibre has a high degree of crystallinity which makes dyeing difficult ([3] Gao et al. , 2007). Until now, few attempts to dye flax fibre with natural dyes have been made.
No reports have been found in the literature of the use of brown pigment from chestnut shells (BPFCS) to dye textiles. In fact,...