supply chain

chemicals and synthetics used in making denim

These days, cleaning up the denim supply chain focuses mainly on water and energy use.  However, that misses a big part of denim jeans' environmental footprint. A lot of chemicals go into making a pair of jeans. 

At every step of the production chain, chemicals are inserted to facilitate some sort of process. Synthetic petro-chemicals are added in the spinning process to make the cotton stretchier. The dye bath, which is one of the most chemical intensive steps, contains all sorts of dye fixatives, oxidizing agents, reducing agents, and enzymes to bind the synthetic dye to the cotton. To get the yarns stiff enough to run through the loom, the material is sized with PVA, resins, and waxes. After the fabric is woven, the desizing process uses acids and enzymes to dissolve those chemicals that are coating the yarns, which are washed  out into the wastewater stream. And in the final step, heavy bleaches and lightening agents are used to create fades and finishes, to give that "worn in" look.  

These chemicals help give denim jeans the look and feel that the customer wants, and often can help reduce the amount of water and energy needed to dye and process the cotton. At the same time, these chemicals are harmful to the workers who grind it and breathe it, and when not treated properly, will pollute and change the pH of water systems in the surrounding community. Furthermore, there have been few studies conducted to affirm the safety of chemicals on this material after prolonged contact with the wearer's skin. 

In the graphic, customers can now put a name to some of the chemicals used in the making of their jeans. Some of these chemicals have been vetted by by standardization organizations as safe, if treated properly. Others are more dangerous in high volumes. At SOURCE Denim, we are working with environmental organizations like Greenpeace to detox the production process of our denim, and work towards the international goal of Zero Discharge of Hazardous Chemicals. 

Coming up next week...how SOURCE Denim's chemical profile is different than conventional jeans!

In search of environmentally friendly zippers

It's always mind boggling for us to discover that even within the smallest, most seemingly trivial of details, the options are so innumerable that we were paralyzed by information and choice. Within the realm of zippers, there are thousands of options. As one employee at YKK Zippers put it, "If I were to send you a price list, it would be a million pages long." 

Luckily (or unluckily?) the choice for zipper manufacturers in the world can be more or less narrowed down to a small handful of manufacturers. The one that leads the industry is the all-pervasive YKK. YKK, an acronym named after its Japanese founder, essentially has a monopoly on the zipper industry worldwide. And if you've never heard of them, you could probably look down at your jeans, backpack, or sweatshirt zipper and find the tiny letters stamped on each dangling pull.

YKK has managed reign over the zipper manufacturing industry thanks to their proprietary machines which were birthed when the founder made a few alterations to existing machines back in ____. These machines (and subsequent improvements) remain the reason why cheaper knock-off zippers snag, crack, and break while YKK stays strong and sturdy. 

We may not have the secrets to YKK's magical machines, but there is enough information out there for us to learn about what goes into a zipper, which can be broken up into:

  • Pull Tab dangling handle typically made out of metal or plastic.
  • Slider Body apple-shaped piece that slides along the teeth.
  • Teeth or Chain the interlocking part that holds things closed. Can be coiled zipper, otherwise known as a self-repairing zipper made with one long spiral of extruded nylon, or in the case of jeans, a tooth zipper with metal or molded plastic teeth.
  • Tape fabric that allows the zipper to be attached to fabric. It is usually made out of polyester, but other synthetic fiber, vinyl, or cotton tape are also available.  
  • Retainer Box heat sealed plastic that prevents fraying.
  • Stops rectangular pieces at the ends of the zipper to prevent the slider from falling off.

Metal zippers can be made of aluminum or brass (a combination of copper and zinc), some with a chemical treatment to give the appearance of antique metal or a black matte finish. 

Environmental Issues

The supply chain of a zipper involves quite a number of chemical and carbon intensive processes. There are the environmental effects of extracting petrochemicals for polyester and polyamide (nylon) production as well as smelting metal. The zipper production process may involve four of the eleven priority chemicals outlined by the Zero Discharge of Hazardous Waste Group, including Alkylphenol Ethoxylates/Alkyphenols (APEOs/APEs), Per- and Polyfluroinated Chemicals (PFCs), Phthlates, and Organotin Compounds. And some Volatile Organic Compounds such as toluene and xylene are contained in paint and adhesive agents. The polyester used in most zippers prevent them from being fully biodegradable, and the blend with natural fibers often prevents them from being recyclable. 

So what zippers are out there for the sustainable, conscious consumer? YKK has made some visible strides to attempt to address the environmental impact of its products. It has signed on with bluesign, ZDHC commitment towards zero discharge by 2020, has signed on to use the Higg Index to assess 20 of its factories, performs 70-80% wastewater recycling in China and Korea, and is in the process of adopting quick dyeing technologies to reduce water and energy use. In addition, it's Japan headquarters have come out with two lines of eco-friendly zippers.

Under the trademark Natulon, YKK produces one zipper that utilizes a chemically recycled polyester (PET) in its zipper chain and slider and can be iteratively recycled, as well as one that has only the open metal pull made with recycled plastic bottles. YKK Japan had previously made a biodegradable corn-based zipper product called reEarth, though it is no longer listed in its catalog. 

Lampo, a high-end zipper company based in Italy, has an entire page touting its sustainability gains, including reclaiming 60% of its nylon used in molded zippers, recycling brass, and downcycling its zing, cotton, and polyester waste. It has recently opened a plating facility that claims to a 30% reduction in water consumption and has equipped one of its weaving facilities with photovoltaic panels, saving 23 tons of carbon dioxide annually. 

Hong Kong-based TYT claims that its Greengear zipper line is made of 100% recycled polymer. 

The most sustainable option for zippers is to reclaim them from old clothes and reuse them in garments. This is time intensive, though, as removing zippers involve wrestling with tight stitches to avoid shredding the tape. Some sellers on Ebay and Etsy sell bundles of salvaged zippers for the DIYer. 

If your zipper breaks because the slider or pull tab come off, a little company based in Oregon called zipperrescue.com provides a kit that can help you fix your zipper. Or you can figure it out yourself by buying new zipper sliders online or at a sewing shop and following instructions on Lifehacker