To Dye or Not to Dye
By Elisa Sellam, Sushil Hada 9 December, 2013
Sellam & Hada from Birla Cellulose explains how spun dyed viscose fibres can save water & reduce pollution, Sellam & Hada from Birla Cellulose explains how spun dyed viscose fibres can save water & reduce pollution, Sellam & Hada from Birla Cellulose explains how spun dyed viscose fibres can save water & reduce pollution
Dyeing is a water intensive process plus it generally seen as being bad for the environment due to the chemicals used and effluent discharged in the dyeing process. So if there is limited water, the question can literally become to dye or not to dye?
In the traditional textiles dyeing process, the yarn/fabric once produced is dyed further down the process chain. During the traditionally piece dyed VSF (Viscose Staple Fibre) process the dye chemicals attach themselves to the surface of the yarn/fabric being unable to penetrate to the core of the fibres. Hence, with repeated washing, abrasion and exposure to light, the colours fade which results in excessive water consumption as repeated washing required to remove the unfixed or faded colour.
What if there was a solution that would use less water in the dying process AND gives lasting colours despite repeated washing?
“pigment dyes are injected into the mix before the fibre is finally made …
… eliminates the need for conventional piece dyeing & saves ~30 litres/metre of fabric processed”
Enter Spunshades: vibrant, heavy metal-free shades of dope dyed viscose fibre. In contrast to the traditional dyeing processes, Spunshades are manufactured with a technique that places colour pigments in the fibre itself when it is being made/spun – Spundyed.
During the manufacturing process of Spunshades, pigment dyes are injected into the mix before the fibre is finally made.
This eliminates the need for conventional piece dyeing and saves about 30 litres of water per metre of fabric processed. Hence Spundyed VSF is a great product for water conservation.
Where water is saved: Conventional piece dyed vs Spundyed
The differences between the conventional piece dyed and the Spundyed processes are highlighted in Table 1 below:
As can be seen in the chart below, in the traditional textiles dyeing process, large amounts of water is consumed by the bleaching, dyeing & printing processes taking up 62% of the total water consumption.
For 1000 kg of product, the conventional dyeing process requires around 48,500 litres up to 418,500 litres of water. The wide variability in the range reflects dyeing using a batch process or a continuous process – the ranges for each process are set out in Table 2 below:
Since the fibres are already in their dyed form, in the case of Spundyed VSF, the processes of bleaching and dyeing are not required, reducing the washing cycles needed to wash the product after each particular process resulting in a double saving. This is the main area where water is being conserved.
In addition, because the process for Spundyed VSF is short, the amount of steam required for particular processes such as bleaching, mercerization, washing and drying is also reduced.
There are downstream savings too …
There are also significant savings in wet processing costs benefiting the textile value chain.
“…downstream textile processes also conserve water through the elimination of … scouring, pre-treatment and washing saving 84 litres/kg of viscose processed”
With the use of Spundyed VSF, downstream textile processes also conserve water through the elimination of processes like scouring, pre-treatment and washing, saving 84 liters of water per kg of viscose processed.
Finally, as the dyeing operation is not required for Spundyed VSF products, not only is less water required to process the fabric, 50% of the effluent load is also reduced, contributing towards better environmental pollution control.
“as the dyeing operation is not required for spun dyed VSF products … 50% of the effluent load is also reduced”
The process of injecting the dyes into the fibres ensures that the colour is deep seeded inside each and every strand of the fibre, which results in the longevity of colours for apparels and textiles. Spundyed VSF has industry leading levels of colour fastness for wash/rub fastness and light fastness.
So it’s when it comes down to limited water & dyeing, we believe the question should not be “to dye or not dye” … it is “how you dye” that matters.
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Read more from Elisa Sellam →
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