What makes a fabric?

For our first real post, let’s talk fabric! Experienced sewists know that the right fabric choice can make or break a garment. Often when people are first starting out in the world of garment sewing, all of the vocabulary surrounding the fabric industry can feel overwhelming. So let’s go back to the beginning and build our knowledge of fabric from the ground up. Just a note here: even though fabric and textiles of various kinds are used in many industries (like agriculture, healthcare, construction to name a few), we’ll be focusing on fabric meant for garments.

Let’s do a thought experiment about two pairs of jeans. Pair A is made of 100% cotton denim with a density of 12 oz per square yard and woven with a twill weave. Pair B is made of 60% cotton, 37% polyester, and 3% spandex with a density of 8 oz per square yard and is also woven with a twill weave. While some of these words may not make sense to you now, keep them in mind while you read and we’ll discuss how these two garments might differ at the end.

Fabric

First up: let’s quickly define fabric. Fabric is a two-dimensional material that is typically constructed from fibers and yarns. The properties of a fabric depend on what the fiber is made from, how the fiber is turned into yarn, and how the yarn is arranged to create the fabric. The beauty of fabric lies in its versatility. You can make an elegant evening gown out of the most airy, lightweight silk chiffon, or you could make a hard-wearing pair of work trousers out of sturdy canvas that will last for years to come.

Broadly speaking, fabric can be constructed from yarn in three ways. Yarn can be woven, knitted, or arranged in a random distribution, which we’ll call “non-woven.” Weaving is the process of interlacing two or three sets of yarn in an over-under grid pattern on a device known as a loom. If you’ve ever made a potholder from fabric loops as a kid, you’ve woven fabric! Check out this video about how industrial looms work. Variations in the number of overs and unders lend different properties and appearances to the end fabric. A classic example of a woven fabric is denim, which is a type of weave known as a twill weave.

A flashback to my childhood, before children had iPads to keep them endlessly entertained.

Twill weave pattern. Denim is an example of twill weave.

The process of knitting a fabric involves the use of needles to form interlocking loops of yarns. You can think of machine-knitting a fabric the same way you would hand-knit a sweater, except on an industrial scale with much thinner yarns and smaller needles. Whereas weaving involves two sets of yarns, knitting can be done with one continuous yarn. One of the most common examples of a knitted fabric is jersey, which makes up all of those free high school and college t-shirts I’m always trying to get rid of. Check out this awesome video of a knitting machine making a scarf!

Non-woven fabric, made from randomly distributing yarns or fibers, is less common than woven or knitted fabric, but it still has important applications in garments. If you are a sewist, chances are you’ve used non-woven interfacing like this sold by Pellon. One nifty property of non-woven fabric is that the material is isotropic, which is a materials science word that just means it has the same properties in all directions. Woven and knit fabrics have different properties (like stretch) in different directions, which makes them anisotropic.

Fibers and Yarns

So now that we’ve talked about how fabric comes together, let’s talk about its parts. A fiber is a substance with a length much longer than its width. Fibers can come from either natural or man-made sources. The length and width of a fiber can vary greatly depending on what material it’s made of. Words used to describe fibers could be warm, strong, absorbent, stretchy, smooth, and many others.

(A) An electron microscope image of cotton before fibers start to grow. (B) An electron microscope image of cotton fibers. (C) Fully mature cotton bolls.

I’m going to categorize fibers into two broad categories based on the material they’re made of: natural and man-made. I’m using man-made here instead of the word “synthetic” because there are some man-made fibers that come from natural origins. Natural fibers used for garments can come from plants (like cotton and linen) and animals (like wool and silk). Man-made garment fibers can come from plants (like rayon, viscose, and acetate), animals (did you know you can make fibers from milk?? ), and synthetic polymers (like polyester, nylon, and spandex). Typically, synthetic polymer fibers are made from crude oil, but there is a growing industry of synthetics made from biological sources (called biosynthetics).

Natural fibers are already in fiber form when they are created by plants and animals in nature. Nature has already done the fiber-izing part of the work for us. Man-made fibers must be created via chemical reactions, then extruded into fiber shape. This means that natural fibers are limited in how long they can grow, whereas man-made fibers can be indefinitely long.

Rayon, viscose, lyocell, and acetate start out from plant matter, but go through various chemical reactions before they are formed into fibers, which is why they’re classified as man-made. These types of fibers are referred to as regenerated cellulose fibers, because the cellulose is chemically broken down then re-formed. One common use of rayon is in Hawaiian shirts. These types of fibers are very soft and breathable. They are prone to wrinkles and are biodegradable.

Usually natural fibers are the most comfortable next to the skin because they are breathable, which means they allow moisture from your sweat to pass through the fabric. They can often withstand high heat and are biodegradable.

Synthetic fibers are typically very durable and can also be extremely stretchy (like spandex). They are usually not very heat resistant (have you ever accidentally melted polyester with an iron?). Some synthetic fibers are biodegradable under the right conditions, but many are not.

Usually in the fabric-making process many fibers are made into yarn. Fibers are twisted together to bind them into a continuous strand. This is known as spinning. Natural fibers need to be aligned parallel to each other in order to be twisted into yarn. The twisting process strengthens the yarn so that it is stronger than the individual fibers that make it up. The amount of twisting in yarn will change the appearance of the final fabric. Low-twist yarn creates smooth fabric, and high-twist yarn creates crinkled fabric like crepe.

Schematic of fibers being spun into yarn.

Finishes

After a fabric is created it is usually treated in some way to enhance or modify its properties. These treatments are known as finishes. Common finishes include wrinkle and stain resistance treatments on pants. Some fabrics, like velveteen, are brushed to create a soft feel. Finishes can be mechanical or chemical processes (or a combination) and might not be visible to the naked eye. Fabric sold without any finishing is called gray goods, or griege goods. A common example of gray goods is the muslin fabric that sewists use to make test garments before we use our fancy fabric on the real garment.

Putting it all together

Let’s go back to our two pairs of jeans from before. Even though the fabric for both pairs has the same weave, the two jeans will have different properties. Which pair of jeans would be most likely to be a jegging-style? Since jegging are really tight fitting, they need to be able to stretch over our body, so we would need some spandex to facilitate that stretch, making pair B the better choice. What about the lifetime of pair A vs. pair B? The synthetic fibers in pair B (especially spandex) will be degraded over time by the heat from the dryer and the jeans will lose their shape. On the other hand, pair A will soften and mold to your body over time. Since pair A is made from denser fabric, it will also likely have an advantage in lifetime, although it might feel stiff and heavy for a while before the jeans are broken in. When each pair does finally meet the end of its life, pair A would decompose in a landfill in around 5 months, while pair B may take as much as 200 years to fully decompose (although I would highly encourage you to recycle or upcycle your worn-out clothes if possible).

Hopefully by now it’s clear that the fiber choice, yarn creation process, fabric construction method, and finishes all come together to determine the properties of the fabric that make up your garments. We need clothing that can serve a wide variety of situations, and the diversity of fabric reflects those needs. If you (like me), are eager to hear more details about fibers, yarn, and fabric, fear not, because I have posts planned to delve deeper into each topic. As always, feel free to leave comments with more knowledge or to suggest more topics!

Resources

All images (except the ones I created) are linked to the original source where I found them. Those sources also served as references for the topics discussed.

The textbook Textiles by Kadolph and Marcketti (12th edition) was also super helpful in putting all of this information together. Being a textbook, it wasn’t cheap, but if you’re interested in textile science I highly recommend it.

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