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What is Cupro Fabric: Properties, How its Made and Where

by Boris Hodakel  • December 11, 2019 • 5 min read

Fabric name Cupro
Fabric also known as Cuprammonium rayon, cupra, ammonia silk, Bemberg
Fabric composition Recycled cotton (or other plant) cellulose exposed to copper, ammonia, and caustic soda to result in a semi-synthetic textile substance
Fabric possible thread count variations Cuprammonium rayon is prized for its extreme fineness
Fabric breathability Relatively low
Moisture-wicking abilities Moderate
Heat retention abilities Moderate
Stretchability (give) Reasonably stretchy
Prone to pilling/bubbling High
Country where fabric was first produced USA
Biggest exporting/producing country today China
Recommended washing temperatures Cold or warm
Commonly used in Fine garments, shawls, eveningwear, lingerie, blouses, summer dresses, other light and form-fitting clothing

What is cupro fabric?

Every garment made with natural fiber reaches the end of its lifetime eventually. In most cases, cotton garments are discarded after use, but your old t-shirts can also be recycled to make a textile sometimes referred to as “cupro” or “cupra” on Chinese textile websites.

Cupro fabric is recycled, which appeals to our environmentally-minded sensibilities. At the same time, however, cuprammonium rayon production involves large quantities of copper, ammonia, and caustic soda, all three of which can be toxic when they aren’t disposed of properly. What’s more, cupro fibers must be bathed in a variety of toxic chemicals before they harden, which exposes the environment to further harm.

While cupro isn’t strictly synthetic, it’s hardly a natural fiber either. After being exposed to ammonia, copper, and caustic soda, the chemical structure of the cellulose in cotton or any other plant product changes dramatically, which makes cupro yet another example of a Chinese rayon derivative marketed as a natural or recycled fiber.

Examples of similar fibers include lyocell and tencel, both of which are championed extensively by government-controlled Chinese textile manufacturers. In the end, rayon-type fabrics like cupro belong in a new category of textiles that, while recycled, may have the same negative impact on the environment as fully synthetic fibers.

Properties of cupro

Cupro is generally prized for these qualities:

  • Fineness
  • Elasticity
  • Sheerness
  • Easy mixture with other fabrics

While it isn’t the most durable rayon derivative, cuprammonium rayon is one of the synthetic fabrics that most closely resembles silk, so it’s often used to replace garments traditionally made with this natural fiber. Cupro is nothing like real silk, however, and it’s important to touch on some of the drawbacks of this fabric to be fully fair:

  • Ignites easily at temperatures above 180 degrees
  • Chars when ignited
  • Leaves behind a residue containing significant concentrations of copper

Cuprammonium rayon cannot be washed in hot water, and unlike natural fibers like wool, cuprammonium doesn’t burn cleanly.

How is cupro fabric made?

Cuprammonium rayon is made by exposing the cellulose of a plant product, such as cotton clothing, to a mixture of ammonium and copper. These two elements combine with the cellulose to make a new substance, and then the mixture is dropped into caustic soda and extruded through a spinneret.

The extruded strings are then immersed in a series of hardening baths that reconstruct the cellulose and remove the ammonia, copper, and caustic soda. In some cases, these baths may be reused multiple times, but no matter what, cuprammonium rayon baths must be disposed of at some time in some place.

How is cupro fabric used?

Cuprammonium rayon is almost exclusively used in apparel, with scarves being one of the few accessories that also sometimes include this fabric. In many cases, cupro is mixed with natural or synthetic fibers that give the finished garment or accessory different attributes.

Apparel applications of cuprammonium rayon when mixed with other fabrics include blouses, tank tops, t-shirts, sports bras, and other light, intimate apparel. On its own, cupro is most commonly used in thin, sheer garments like form-fitting dresses.

Where is cupro fabric produced?

Like all other synthetic textiles, China is the world’s major producer of cuprammonium rayon. Despite the environmental concerns associated with cuprammonium rayon production, China continues to export tons of “cupro” to Western nations every year.

How much does cupro fabric cost?

Cuprammonium rayon is produced explicitly for its low cost. Vast quantities of waste cellulose can be acquired for very little money, and by mixing this cellulose with a few basic elements, it’s possible to create entirely new cellulose fibers from scratch.

The profit margins of this endeavor are enormous assuming volume movements remain high, but to the detriment of rayon manufacturers, consumers continue shunning artificial fibers and embracing organic alternatives. As more holistic fiber recycling processes become available and people simply stop using synthetic fabric, cuprammonium rayon production will be driven out of business.

What different types of cupro fabric are there?

While a lot of different brand names and slang are used for cuprammonium rayon, they all refer to the same recycled substance. Here are some of the related terms you should familiarize yourself with:

1. Cuprammonium rayon

The scientific name for cupra, cupro, ammonia silk, or Bemberg.

2. Cupra/cupro

Instead of being registered brand names, it appears that these terms are simply Chinese factory slang for cuprammonium rayon.

3. Ammonia silk

You’d think that fabric marketers would have realized long ago that ammonia isn’t something you want to have come in contact with your body, but cuprammonium rayon garments are still referred to as “ammonia silk” on many Chinese textile websites.

4. Bemberg

Back when manufacturers were still trying to make cuprammonium rayon in the United States, it was patented by a company called J.P. Bemberg under the trade name “Bemberg.” It’s still the same cuprammonium rayon, however.

How does cupro fabric impact the environment?

Despite being recycled, cuprammonium rayon has a decidedly negative impact on the environment. Rather than seeking solutions to environmental crises, manufacturers of cupro and similar fabrics are simply trying to figure out how to make money with waste products.

Over the years, China has gradually accumulated the world’s waste at extremely low cost, and lab scientists in Beijing have worked tirelessly to develop new ways to transform this waste material into usable fabric. Copper, ammonia, and caustic soda are all cheap, and the cupro manufacturing process itself is likewise inexpensive.

Since so little regard is given to the safety of mixing cellulose with ammonia and copper and turning it into wearable fabric, it stands to reason that equal disregard is paid to the proper disposal of these toxic substances once the cuprammonium rayon production process is complete. China’s synthetic textile factories are reviled around the world as havens for modern-day slave labor, and as a product of said factories, cupro certainly does not further the cause of environmental stewardship that we all share.

Cupro fabric certifications available

“Cupro” as a brand name or slang term is not eligible for any specific certifications. Likewise, it’s telling that cuprammonium rayon production in the United States was given up due to the inability of manufacturers to comply with basic air and water protection regulations. Given the fact that America has long suffered under relatively lax environmental regulations, cuprammonium rayon must be an unusually polluting substance.

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About the author:

Boris Hodakel is the founder and CEO of Sewport - an online marketplace connecting brands and manufacturers, former founder of various clothing manufacturing services. He is passionate about e-commerce, marketing and production digitisation. Connect with Boris on LinkedIn.