Summary

A number of visits have been arranged by XYZ Processing Industry (Pvt) Ltd. and the problems (particularly in the regard of pH stability of dyeing bath) were discussed with the management of industry. After studying all the process and working conditions we have done initial study to solve the problems which management of XYZ Processing industry were facing. In this preliminary study we prepare different buffer solutions and dyed two sets of shade i.e. Olive and Beige, and compared the results on same shade by using XYZ Buffer solution.

The corresponding colorimetric data for each dyeing with different buffer solution are displayed in the attached sheets. By using buffer solution 1, 3 and 7 the values of K/S are higher than Buffer Solution No. 8, which is of XYZ industry. A higher value of K/S means the higher depth of colour. Similarly lower value of L* for the same buffer solutions also proves the results. The hue of these solutions are also according to Munsell equation, having the lower value of a*. On the other hand due to the higher value of a* the hue has considerably change for XYZ's buffer solution. This high value of a* may impart the fastness results also. By considering this data and on visual assessment of shade, Buffer Solution No. 1,3 and 7 are found to be most suitable in terms of required shade and also the chemicals used which ultimately reduced the production cost.

Introduction

Colour has been playing a dominant role in the life of man from time immemorial. Even in the prehistoric times, the ancestors of man must have noticed (perhaps with or without understanding) the abundance of multitude of colours worn by nature. Thus he must have wondered at the spread of transient bright golden colour on the diffused clouds and on the landscape during dawn and sunset, the "VIBGYOR" colours of a rainbow, the vast expanse of the blue sky on a cloudless day or acres and acres of land crowned with chlorophyll dominated green coloured vegetation or even an infinite variety of plants and trees, bearing flowers and fruits of varied colours of an almost innumerable combination of yellow, red and blue hues in different depths and shades or even the multi-coloured stripes and dots on the bodies of the birds of the sky, animals of the land and the fish of the sea. With the growth of intelligence in man, he must also have noticed that most of the colours he saw in nature (colours at sunset, flowers on plants etc.) were not permanent; the fading of the colours of leaves changed to yellow or brown due to ageing, etc. There might have been an urge in him to try to retain the pleasing colours for longer periods and working in this direction, he might have found that certain plant juices and extracts from organisms produced colours which would last long.

Textile is the backbone of Pakistan's economy and shares more than 60% of the exports of Pakistan. Cotton being the main crop in Pakistan attracts more attention, as it is still the principal raw material for the textile industry in the world. Polyester is second important fiber used in textile made up, as a pure as well as blends with cotton, Polyester cotton can be dyed with disperse and direct dye.

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About the Authors

The authors are Scientists at Pakistan Council of Scientific & Industrial Research (PCSIR) Lab Complex Karachi.