The one thing you should look for on clothing labels when you go shopping

It might seem that fabrics made with plastic such as polyester would be more environmentally friendly if they had some natural fibers mixed in. But when plastic and natural fibers are combined into one fabric, it becomes more difficult to care for and reuse over the course of its life.

Blended fabrics are one reason clothes recycling is still rare and why heaps of them pile up in landfills. Sorting and detangling blended textiles is costly and time-consuming. Accidentally allowing too much of a synthetic fiber such as spandex into the recycling stream can cause the whole process to break down, destroying the machines.

Yet clothing made of natural-synthetic blends such as cotton and elastane — a material often used for denim jeans — is increasingly common, said Georgia Parker, the innovation director at the apparel sustainability initiative Fashion for Good. In Europe, nearly a third of all clothes are made with these fabrics. “Our findings underscore the prevalence of blended fabrics in the industry,” Parker said.

Here’s what you need to know about what fabrics to pick the next time you’re shopping.

The problem with blended fabrics

Compared to 100% natural fibers or other biodegradable materials such as viscose, or rayon, which is made from a wood-like fiber, blended synthetic fabrics can be more durable and withstand more stress. They can also feel softer and smoother, and perhaps more importantly, they can be cheaper, according to textiles researchers.

That low cost makes the fast fashion problem worse, inspiring people to buy more than they need: The average American buys more than one new piece of clothing per week.

Because they’re not easily recyclable, these textiles eventually end up in landfills both within and outside the United States — typically in countries such as India, Pakistan and China. That means the resources that went into making them are essentially wasted, said Karen Leonas, a professor of textiles sciences at North Carolina State University.

Clothes made out of natural fibers, such as cotton or linen, are easier to take apart and recycle — though there are few facilities to process even those materials. Still, experts say that recycling technology is improving and that apparel companies will invest in it if enough customers signal they want their clothes to be more sustainable.

“The consumer really drives the product that goes out there,” Leonas said. “If consumers were demanding 100% single-fiber products, and they were willing to pay for it, there’s a return on investment that companies can get from that if they launch buyback and recycling programs.”

What you should look for in a label

Avoid blends with synthetic materials. Polyester, acrylic and spandex shed plastic fibers every time they are washed in a machine. Washing synthetic textiles is the single greatest contributor to ocean microplastics, which eventually enter the food chain, animals’ bodies and our own. The exact health effects of microplastics are still unknown, but researchers are concerned they could be causing or exacerbating serious health problems. While clothing made of natural fibers also releases fragments in the wash, those materials will biodegrade.

“Polyester doesn’t go away, so by its very nature not demanding its presence helps us keep it in check,” Kelly said.

But, if choosing between a blended fabric and 100% polyester, go with the pure polyester garment. Because polyester fibers are made of plastic, they can be easily recycled and reused over and over again. Enough polyester clothing exists today that the fashion industry should never need to make any more new material, said Becky Flax, a colleague of Kelly’s at Jefferson University’s textiles design program. Labels will often indicate if clothing is made from recycled polyester.

Natural fiber blends can be OK. When choosing between different types of biodegradable and natural-material fabrics, you should think about fiber families, Flax said. Different types of cotton — such as recycled cotton and new cotton — will blend well together and be easily separated, and the same goes for cotton and linen blends.

By contrast, a mix of wool and cotton is harder to recycle because the two fabric types are so different that they are hard to separate, even though they are both made of biodegradable materials, according to Flax.

Know your natural fibers. Natural and biodegradable fabrics are not equal in terms of their environmental impact.

• Cotton grown organically can create lower greenhouse gas emissions and use less water than conventionally grown cotton.
• Linen and hemp — both known as bast fibers because they come from the bark of plants that grow like a stalk — require fewer resources to grow and are more durable than cotton, but they can be more difficult to dye and require more water, energy, and chemicals to transform into usable fibers.
• Wool can be sheared every year from the same sheep, but how that’s done and where the sheep are raised will determine how much wool is used, how much is wasted and whether it’s dyed sustainably. Unfortunately types of wool are rarely labeled for consumers.
• Lyocell, which is made from wood pulp, can be produced with resource-intensive methods and pollute water. But it can also be made in more environmentally friendly ways, Leonas said. Tencel, for example, is certified for sustainability by the EU Ecolabel.

So how do I choose?

Each type of fiber has trade-offs, so avoiding natural-synthetic blends is not a panacea, Leonas, Kelly and Flax cautioned. Consumers should read every label and research the materials, treating their clothes as if they are art or an investment, they say.

They recommend doing research on the specific company you’re purchasing from, looking for where they source their materials and what certifications, if any, they may have. The more you learn about what you’re buying, the better you will care for it. For example, if you know that wool is naturally odor-resistant and absorbs more moisture than many other fibers, you might choose wool-based athletic clothing over synthetic because you can wash it less.

And if you’re choosing between a new 100% cotton T-shirt or a thrifted one made of a cotton-synthetic blend, always opt for thrifted. “The bottom line is that diverting it from the landfill is increasing the longevity of the particular product,” Leonas said.