Chlorine-free Wool

Why wool is treated with chlorine

Raw, untreated wool has scales that make it itchy and coarse and cause it to shrink, so most wool fabrics are treated with chlorine to reduce the scales. But chlorine is a pervasive pollutant that’s especially harmful to organisms living in water and soil. We remove the scales from our merino wool fibers using a unique chlorine-free process that’s Bluesign approved.

Machine-washable wool was made possible by the development of a chlorination pretreatment of the barbed scales combined with the application of a thin polymer coating. These treatments make wool fibres smooth and allow them to slide against each other without interlocking. This also makes the wool feel comfortable and not itchy. Millions of pounds of wool are processed each year using this chlorine-based method.

The problem with chlorine

Unfortunately, this process results in wastewater with unacceptably high levels of adsorbable organohalogens (AOX) – toxins created when chlorine reacts with available carbon-based compounds. Dioxins, a group of AOX, are one of the most toxic known substances. They can be deadly to humans at levels below 1 part per trillion. Because the wastewater from the wool chlorination process contains chemicals of environmental concern, it is not accepted by water treatment facilities in the United States. Therefore all chlorinated wool is processed in other countries, then imported.

While garments made from chlorine-treated wool do not pose any risk to the consumer, the primary environmental concern is with the industrial wastewater from chlorination facilities. Patagonia’s support of chlorine-free wool is therefore similar to our support of organic cotton, in that the final product is not the issue but rather the environmental impacts of the supply chain are the reason for choosing these materials.

For more information about chlorine, visit the Chlorine Institute website.

For a report about chlorination byproducts, visit the non-profit research organisation Environmental Working Group.

How we minimise the impact

There are a few alternative processes that remove the tips of the barbed scales without the use of chlorine. Some of these methods use another strong oxidising chemical, such as ozone or hydrogen peroxide, which in wastewater treatment breaks down into oxygen and water. Patagonia chooses chlorine-free and AOX–free methods to make machine-washable wool garments with next-to-skin comfort.


Background Photo: by Terri Laine