You might think that factories are washing your jeans because they want them to be nice and clean when you buy them in the shop, but that is not the case. There is so much going on in the laundry of a finishing factory: changing the feel, the colour, the texture, the properties and the look of garments.
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After your jeans are cut & sewn, they’re “finished” where coatings are added or dye is removed for different looks. This is where we have seen a great deal of work in creating more sustainable options that use fewer resources and require less time. Ozone gas and lasers have been instrumental in removing indigo to create vintage washes and whiskering that was generally produced using harsh chemicals like Potassium Permanganate (PP SPray) and manual scraping.
Wastewater has been a major issue with processing denim. After denim has gone through the washing process, toxic sludge is left and disposed of in unethical and unsustainable ways.
They say in China you can tell the next trendy colour by looking at what colour the rivers are 😞
Effluent Treatment Plants are just as important in the washing process as in dyeing of the indigo. They use chemicals, bacteria, filters that need to be changed, and a lot of electricity, the best practice is definitely to avoid polluting the water, and when necessary then cleaning it. What exactly is removed from the water? Sludge is a combination of very small particles of cotton, particles of stones used in the wash, and chemicals. Do you have a dryer at home that requires you cleaning the filter at every usage? On an industrial scale that is the equivalent of sludge. The types of sludge of course depend on what initially goes in the water that is cleaned in the ETP: what fibres, chemicals and stones are used, and this will define the ways in which it can be disposed of.
After the garments are washed they also need to be dried. You can imagine that machines that can dry up to 100 jeans at a time need a lot of heat and power, meaning that they consume steam and electricity in vast amounts. Why don’t they hang the jeans like they do in Italian towns? Some factories have started installing conveyor belts that allow the jeans to be dry up to 85%, and then go in dryers for a very short time to become softer.