Not sure what synthetic fabrics are?

Sometimes when we are knowledgeable about a topic, we may make the assumption that others understand what we’re talking about. I came to this realization when a customer asked a retailer a textile science question. This retailer sells laundry bags that collect microfibers released  into the washing machine from synthetic fabrics. The customer’s query was “what are synthetics that should be put in the bag”. Not everyone knows what synthetics really are, and how they are different from natural fiber fabrics. The following provides the answer to this very good question.

There are three major groups of fibers, natural fibers, and manufactured fibers consisting of cellulose based and synthetic fibers. Natural fibers are further divided into protein (animal) and cellulose (vegetable) sources. Manufactured cellulose based fibers include rayon (viscose) and lyocell (Tencel). The latter two fibers are manufactured like synthetics, but are composed of plant cellulose from a variety of sources such as trees and bamboo.

Natural fiber chart

Manufactured fiber chart

Synthetics

We call fibers synthetic because they are a result of chemical synthesis of raw materials like petrochemicals. There is nothing natural about a synthetic fiber because they are made in a lab. They can be produced to resemble almost any natural fiber, but their underlying structure and properties are very different from natural ones. Manufacturers produce synthetics because they are strong, easy to care for, resistant to mildew and pests, long-lasting, and are inexpensive to make. Much to my dismay, polyester is now the most manufactured synthetic globally, and makes up around 60% of the clothing on retail shelves.

They do possess desirable properties and are better than they once were, and are suitable choices where performance is key, in activewear, swimwear and outerwear. But for the most part their characteristics are problematic for our planet and our everyday clothing. I’ve talked at length in previous posts about their environmental impact. Briefly, synthetics like polyester do not biodegrade like natural fibers, and the processes involved in the manufacture of them are detrimental to the environment. Today the prevalence of synthetics in clothing is simply because they are easier to make and cheaper than natural fibers.

Properties

The hygroscopic qualities of animal fibers help fabrics to breathe and absorb a lot of moisture, while still feeling warm and dry to the wearer. Because synthetics absorb very little moisture, they do not breathe. Some garments can feel clammy and uncomfortable in warm climates. For this reason you’ll often see synthetics blended with natural fibers. 

Their lack of moisture absorption contributes to the build up of static electricity, particularly in dry climates. Static is a magnet for dirt and dust, pulling them deeper into the fabric. This actually means you need to clean synthetics more often, leaving microfiber residue in the washing machine. Note: Another definition for microfibers is a type of woven fabric, densely made from synthetic fibers.

Pilling is a problem with synthetics. You’d think this wouldn’t happen because they are long-lasting. The reason for the excessive pilling is their high strength. These fibers are so strong they get entangled and don’t break off the surface of textiles. The short, staple fibers from natural sources easily break off the surface, with little or no pilling.

Synthetics react differently to heat and flame than natural fibers. Protein fibers like wool self-extinguish, cellulose burns, and synthetics melt. Burning synthetics produce toxins and cause severe burns. Most synthetics have very low melting points, and can melt from high dryer and iron temperatures. Fabric labels will often read no-iron or only at low temperatures.

Most Common Synthetics in Hand Knitting Yarns – Nylon and Acrylic

Nylon is the generic name for one of the fibers found in the synthetic group polyamides. Sometimes you’ll notice the word “polyamide” on the yarn label instead of nylon. The most common material used for its production is petrochemicals. Nylon was first developed in 1935 by the Dupont Company. It was introduced prior to WW11 as a silk alternative for hosiery, but also for the production of parachutes.

Nylon is one of the strongest textile fibers and is commonly found in hand knitting yarns. Wool with a small percentage of nylon is a common blend found in many sock yarns. Nylon is also found in novelty yarns like ribbon, eyelash yarns, and as a binder thread for brushed mohairs.

The first production of acrylic was around 1950 as a replacement for wool, because it was less expensive and washable. The chemical base of acrylic is 85-95% vinyl cyanide or acrylonitrile. Orlon is a trade name for one type of nylon. The best applications for acrylic are as “novelty” yarns such as fake fur.

Ask any knitter what they think about synthetics, and an argument or strong opinion may ensue. My affinity has always been towards natural fibers. I am thankful that the majority of hand knitting yarns are composed of natural fibers, for their beauty, quality, and performance. We will never obliterate synthetics from our clothing and other textiles, but my hope for the future is that the fiber composing a fabric will be chosen because it’s the best for the garment, and not because it is cheap and easy to make.