Breaking Down the Chemicals Used in Each Stage of Textile Production
Textile production takes place in several stages, all of which require different types of compounds to aid in cleaning, strengthening, improving aesthetic quality or preservation.
"Some of these chemical are hazardous to humans, animals and the environment. "
Below is a look at the broad stages of textile production and the chemicals used in each stage.
1| Fibre production
The production of natural fibres, particularly plant fibres, requires the use of fertilisers, fungicides, pesticides and insecticides.
These examples of cotton and wool production will elucidate further:
Cotton, being the most widely cultivated source of plant fibre, utilises the largest amount of these chemicals. Further, when cotton is machine-picked, it is sprayed prior to picking with a chemical defoliant, that assists the unnecessary leaves to fall to the ground.
The same case applies to wool production. It would take years to yield enough quantities of wool for textile production if animals are left to grow naturally. To promote faster growth and lower animal mortality, sheep rearers use requires organo-phosphorous pesticides to control pests. Additionally, once the sheep are sheared, their wool has to be scoured and washed using chemicals, which also contaminate water sources. The use of chemicals is also experienced in production of synthetic fibres.
The production of synthetic fibres also uses a large number of chemicals. Synthetic fibres are made from fossil oils, which in itself encourages environmental degradation. To polymerise the petroleum extracts materials into fibres, different combinations of chemicals are used, including acids and salts.
2| Fibre to Yarn
After harvesting or manufacture, fibre is spun into yarn. During this stage, chemicals in the form of spinning oils and additives are used to add strength and consistency to the fibres as well as to minimise friction while spinning.
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3| Yarn to Fabric
Fabrics are made from yarn and can either be knitted, woven or non-woven.
Lubricants, and sizing chemicals are used in this stage to increase yarn strength and reduce friction. For non-woven fabrics, chemical solvents and adhesives are added to bind the yarn together.
4| Fabric pre-treatment process
Pretreatment is done on fibre, yarn and fabric to enable dyes and other chemicals to adhere better. Fabrics are subjected to pre-treatment steps based on the type of fibre used. Some of the chemicals used include:
Detergents and solvents for washing
De-sizing chemicals to remove the sizing chemicals from the warps of a woven fabric e.g Sodium, Ammonium or Potassium Persulphate, dilute Sulphuric acid or Hydrochloric acid
Bleach for whitening fibres. Bleaching makes it easier for the fabrics to absorb dyes easier. e.g Oxidizing bleaches such as hydrogen peroxide or reducing bleaches such as Sulphur dioxide
Mercerizing chemicals using concentrated caustic alkali. Mercerizing allows plant fibres to become stronger and accept dye easier.
Acids for carbonizing fibres. Carbonizing removes impurities like pods and seeds from wool.
Scouring chemicals for removing fats, wax and grease from natural fibres. The table below shows some of the chemicals used in the scouring process.
5| Dyeing and printing
When dyeing a fabric, different fixation chemicals are used to make the dyes adhere and washing chemicals are also used during the washing process. When these dyes find are dumped into the environment as waste, it can take them up to 46 years to biodegrade.
When printing full-width fabrics, resins or binders are used for sticking printing pigments on to the fabric. Plastisol printing is more common for garment printing. The process uses a PVC-based adhesive that contains phthalates, which are known to cause hormonal defects in developing children.
The printing machines emit gases such as volatile organic compounds (VOCs) and ammonia.
6| Finishing treatments
It is estimated that the number of chemicals used from pre-treatment, to dyeing and finishing range between 20 to 30. The effluent from these chemicals usually contains heavy metals, which are harmful when they contaminate water sources and soil.
A few examples of chemicals used for finishing treatment include:
Softening- polyurethanes and silicones
Stiffening-starch resins or polyvinylalcohol
Crease resistance- formaldehyde-based resins
Water, oil and dirt repelant-fluorocarbons
Anti-bacterial treatment-silver, triclosane
7| Garment production and shipping
Once the fabrics are finished, they are used to make end-user products such as clothing items. This process produces pollutants in the form of dust and formaldehyde fumes from the textiles being cut.
Before being shipped to shops, the finished garments are first treated with biocides to protect against mould during transportation and while on shop shelves.
Roughly 8000 chemicals are used in textile production. Their impacts range from environmental to the health of workers and consumers.
Given that the labels on textiles don’t show the chemicals used in the production process, consumers are none the wiser when buying textiles and this makes it difficult for them to make informed choices that are healthy for them as well as the environment.
“Roughly 8000 chemicals are used in textile production. Their impacts range from environmental to the health of workers and consumers.”