Cotton is the backbone of the world's textile trade. It has many qualities and countless end uses, which make it one of the most abundantly, used textile fibres in the world. It is a seed hair of plant of genus gossypium, the purest form of cellulose found in nature. However, cotton is one of the most problematic fibres as far as its general wet processing or dyeing is concerned. Quite frequently, the problems in dyed cotton materials are not due to the actual dyeing process but due to some latent defects introduced from previous production and processing stages. Often, the root-cause of a problem in the dyed material can be traced as far back as to the cotton field.
The dyeability variations are cotton obtained from different sources. It has been suggested that the substrate should be obtained from a single source, wherever possible, in order to keep the dyeability. Variations than other, those dyes should be selected for dyeing which are less sensitive to dyeability variation. In dyeing, if resultant shade for a dye mixture passes the quality examination after its first dyeing, the product is called a right-first-time product. The process producing the right-first-time product is thus called a right-first-time process: one that is economical because it consumes the least energy, labor, and time etc. To produce a right-first-time product, process control is essential for dyeing and, to enable this, many modern dyeing control systems have been developed. Unfortunately, errors in the dyeing operation will still sometimes occur. Therefore employing a low-sensitivity recipe in dyeing may be an alternative approach. Should dyeing errors occur, the less sensitive the recipe is to such errors, the more chance there is that the resultant shade will successful.
About the Authors:
The authors are textile scientists at Pakistan Council of Scientific & Industrial Research (PCSIR) Lab complex, Karachi.