A Step-by-Step Chemical Recipe to Dye Commercial Cotton with Natural Indigo Dyes in an Open Bath for the Beginners and Artisans

With the emergence of the need for natural bio-based chemical dyed wearable substrates, such as apparel or textiles, the demand for value-added craftsmanship induced on apparel or textiles is also on the rise. Local artisans are also exporting their value-added apparel products by diversifying their product range creating more local employment. Nowadays global retail fashion houses are also introducing naturally dyed wearable substrates for the increasing consumer demand for eco-friendly green products and concerns with global climate change. Small and medium entrepreneurs (SMEs) or artisans are also keeping pace with this new trend of offering such natural dyed products to the consumers. Therefore, this has created a new space for local artisans to produce various designs using natural dyes. The natural indigo dyed product is in great demand in the high-end fashion retail houses as well as in boutiques. However, little knowledge is available for the artisans to apply indigo vat dyes naturally extracted from the leaves of Indigofera tinctoria plants, because of the lack of technical knowledge, complications of chemical recipe parameters, zero access to expensive heavy industrial machinery. Therefore, an attempt was taken to formulate an easy chemical recipe to dye cellulosic cotton fabric with natural indigo dyes without the need of any industrial dyeing machinery as well as conforming proper fastness to rubbing and washing, which are basically the major concerns for any vat dyed commercial products to meet the export demand. The chemicals used for this recipe formulation are also commercially available and cheap, making it an appropriate choice for local artisans to use and sell their finished end-product to exportable markets. The most important finding was the effect of vatting temperature to act as a major player to form water-soluble leucoindigo vat dyes from their insoluble solid dye state. Azo test was also conducted to confirm the absence of any carcinogenic amine containing any azo functional group that is harmful to the skin. Additionally, two different temperatures, such as 23oC and 30oC was used to produce the vatting recipe required for successful dyeing within 5 minutes at a lower temperature of 40°C, which will not cost any additional expenditure for the local artisans as they can produce this fermented vat on normal atmospheric conditions.