After the cotton is fully grown, it can be picked by hand or with special machines. After harvesting, the cotton still contains contamination such as cotton seeds and  plant residues. Cotton is mechanically cleaned to remove as many plant residues as possible (ginning) before it is baled. The cotton bales are then transported to the spinning factory.

When all fibers are clean and well mixed, the spinning begins. Spinning consists of several steps. First the fibers are carded, to get all fibers neatly laid in 1 direction, using a carding machine and a web of fibers is created.  The web is formed into into coarse strands, called slivers. Next, the sliver is twisted and slowly drawn (stretched) at the same time, creating the yarn. Special spinning machines are used for industrial spinning, which consume energy.

After the cotton yarn has been spun, it can be used for weaving and knitting. However, cotton is naturally a bit yellowish and has a waxy layer. Before it can be colored, it is scoured and bleached (first finishing steps). During scouring, the waxy layer is removed, so that the cotton becomes hydrophilic and absorbs water and therefore also dye. With bleaching, the natural yellowish color is removed and the yarn becomes evenly white. Dyeing of yarns can be done in different ways with different machines and different dyes.

The finishing steps scouring, bleaching and dyeing use (harmful) chemicals and require a lot of water. Chemicals end up in wastewater. Cardoso (2013) gives a number of examples of contaminants that can be found in wastewater after scouring, bleaching and dyeing, such as: pesticides, caustic soda, solvents, metals and salts. After the yarn has been dyed, it must be rinsed well, which of course requires more water. Energy is also needed to heat the water to the right temperature. After dyeing, the yarn is wet and must be dried, which also uses a lot of energy.