Dyeing Coir

Dyeing of coir fibre/yarn is essential for improving the marketability and aesthetic value of coir products and according to customer taste. A dyestuff is most commonly an organic compound, which can be used to impart colour to a substance. A wide range of dyes capable of yielding bright shades of excellent fastness are available for the dyeing of yarn.

In dyeing, the fibre absorbs the dye from the aqueous solution is more or less uniformly coloured.
The uniformity of dyeing depends upon the absorptive power of coir fibre, the nature of the dye and condition of dyeing. The dyed shade usually must be matched against a sample and the fastness of the dyeing must conform to the specified requirement of the consumer.

Traditional method of dyeing coir

In the conventional method, the dyeing is carried out in copper or aluminium/Indalium or G.I. vat of 1.2 M diameter and 0.75 height place on hearth made out of country bricks, fired from below using country wood. The dye vat is sufficient to process 60 kg. of coir yarn or 30 kg. coir fibre with a material to liquor ratio of 1:12 for coir yarn and 1:20 for coir fibre.

After filling with required quantity of water, it is heated from below till the required temperature is reached. The required quantity of dyestuffs and chemicals are added to the dye bath after making into
a paste. The dye bath is stirred well and the material is entered and turned manually at frequent intervals for level dyeing. At the end of dyeing the material is taken out washed in cold water and dried under shade.

Improved method of dyeing coir

The improved method of dyeing process is carried out by highly skilled professionals in the industry using dye vats made of stainless steel and fitted with drainage valve for proper draining of dye effluents. The vats are fixed on hearths made of firebricks with flue pipes for efficient air draught for maximum utilisation of the heat energy. The dyes are taken as per recipes formulated by the Central Coir Research Institute (CCRI), which is available in the shade cards. The quality of dyeing is improved compared to the traditional method of dyeing.

Mechanised system of dyeing

In the mechanised system of dyeing, coir yarn is dyed, comprising of dye vats with forced circulation of the dye liquor in two-directions on uniformly arranged coir yarn for uniform level dyeing. The temperature is controlled as per the requirement by regulating the flow of heating system. After the dyeing operation, hydroextractors are used to drive out of the major part of the mechanically held up water and finally these materials are dried on the endless conveyor dried, for efficient drying. This system of dyeing helps to improve the penetration, shade consistency, uniform dyeing on coir fibre/yarn by the action of temperature efficient and forced circulation of dye liquor and period of dyeing. This method helps to dye large quantities of material at a time avoiding shade variation compared to the other two processes.

Extracted from AgriGold SwarnaSedyam