Chapter 23 - Advances in natural dyeing of silk

Abstract

The chapter comprehensively reviews some recent trends on natural dyeing of silk. In one study, Areca catechu (betel nut) extract solution has been applied as a natural dye on silk. Chemical structure of betel nut extracted solution was confirmed by using FTIR and 1H NMR spectroscopy and thermal properties also measured for determining the proper dyeing temperature. In order to optimize the coloration properties, variable dyeing parameters (temp, pH, and mordant type) were studied. The halochromic effect of synthesized natural dye was analyzed using UV–Vis spectroscopy. Additionally dye build-up, color fastness properties of both fabrics were compared. Onion peels have been fermented prior to dyeing of silk to enhance the dyeing efficiency. The conditions have been changed by mixing the nutrients and microorganisms, and the differences in color and fastness are evaluated. Sucrose and dry yeast (Saccharomyces cerevisiae), important factors affecting the fermentation, have been used as nutrients and microorganisms for fermentation. Fastness to light, washing, and perspiration are found higher after fermentation. The dyeing of silk using fermented solutions made of onion peels shows a distinctive color change and good colorfastness. This may be helpful in developing natural dyeing products of various colors. The dried leaves of Madhuca longifolia have been evaluated for their potential as a source for natural dyeing of silk. The extracted dye has been applied on the silk fabrics and a range of shades are obtained using different methods with or without using mordants. It is found that the mordants have a significant effect on the color of dyed silk fabrics. The dyed fabrics have been tested for various parameters including eco-parameters. The dyed silk fabrics show acceptable fastness properties and are found to possess antibacterial activity. The results show that M. longifolia leaves are promising as a natural colorant, which would in turn pave the way for the discovery of a new range of environmental-friendly dyes for textile materials. Natural dyes have been extracted from camphor plant dry leaves in alkaline medium and are then applied onto silk fabric by exhaust dyeing process. Results reveal that dyed fabrics have excellent UV protection properties, good antibacterial properties, very good colorfastness to washing and rubbing, while fastness to light is poor. Dyeing duration causes change of color. Monascus were cultured and applied in silk dyeing. The bacterial morphology and cultural characteristics of Monascus were investigated. The soap washing and rubbing fastness of Monascus dyed fabric were both rated over Level 4. An ecological low-temperature dyeing method was developed, which provides a basis for practical microbial dyeing of silk fabric.