Wool and cotton are both natural fibers. This means that they are both used to create breathable, comfortable clothing, but the two fibers have very different profiles and uses. There are many scenarios in which one of the two is clearly the better choice, but to know what those scenarios are, you need to understand the key differences between wool and cotton. We’ve talked about the differences between wool and fleece before; now, let’s learn about these two natural fibers and how they compare.
What is Wool?
Wool is the natural fiber produced by animals like sheep, goats, bison, some breeds of rabbit, and a few other mammals. While wool is chemically identical to hair, structurally it is quite different. For starters, wool has a much thinner inner core than hair does, which essentially means that each strand of wool is more like a tube. This is important because that inner structure is part of what makes wool such a good insulator.
Wool has a natural crimp to it, and is somewhat elastic; the stretchy fibers are easily spun and woven into strong cloth. This natural springiness means that wool is great at retaining its shape. Wool fibers can bend upwards of 20,000 times, which means that garments made from wool are high-performing and durable. Wool can also absorb up to ⅓ of its weight in water, which means that it will wick water away from the interior of a garment to the exterior.
History Of Wool
Wool has been used by humans to make clothing for thousands of years. While sheep were first domesticated about 10,000 years ago, these desert sheep were primarily used for meat. It wasn’t until about 6,000 years ago that people began to breed them for their wool. Since then, wool has been used to make clothes for daily wear, outerwear, blankets, carpets and rugs, tents, bags, and any other product that can be made from fabric.
Wool has been highly prized for its ability to insulate, provide water resistance, and prevent catastrophic fires. Because wool burns at a higher temperature than other fabrics and because the char it produces is self-extinguishing, it is the fiber of choice when making clothing for first responders, firemen, soldiers, and other occupations where exposure to fire is likely.
What is Cotton?
Cotton is a plant fiber that was first domesticated and used by people in the Indus River valley around 6,000 to 7,000 years ago. By 6,000 years ago, it had simultaneously been domesticated in Peru; the plant’s global distribution made it a useful resource for numerous societies and civilizations. The fluffy part of the plant that wraps around the seeds is used to create fabric. After the seeds are combed out of it, cotton is then spun into yarn for weaving or knitting.
The cotton industry also sells the fluff that cannot be spun as insulation for other manufacturing processes. Cotton fibers are primarily composed of cellulose. They are long and strong and can be spun into many different thicknesses of yarn and thread, which can then be used to create numerous types of fabrics of varying thickness and stiffness.
Cotton fiber is highly versatile and can be used in many different applications. It is a durable fabric; when the fibers are brushed and stretched, they are also incredibly soft. Cotton is highly absorbent and dries quickly, making it great for moisture control. Historically, cotton was first domesticated in dry, arid climates– it’s ideal for hot places where you need your fabric to breathe.
Lightweight cotton shirts and pants are excellent summer wear and are much more breathable and airy than woolen garments. Cotton is lightweight, but it still has some insulating properties. Cotton is also hypoallergenic and is delicate enough to be used for baby clothing.
Advantages of Wool
For the outdoorsman, the traits of wool that make it great for gear are primarily related to warmth retention and moisture-wicking. These properties come from the natural structure of wool fibers, and cannot be met by any other fiber, synthetic or natural. Even fur can’t be used like wool is, because it’s much more difficult to spin and weave.
Wool retains warmth due to its structure. While the thickness of the fabric alone can provide some insulation, wool’s real insulating properties are similar to those of down. Tiny scales on the outside of each shaft of a wool fiber let the woven fabric trap tiny pockets of air that have incredible heat resistance. This is why many desert nomad groups, like the Bedouin, make their tents from wool. On a cold day, these air pockets trap your body heat and prevent it from escaping into the cold air around you.
Wool is a hydrophobic fiber because it has a high lipid content. Each fiber is soaked in the natural oil that sheep produce, called lanolin. Most of the lanolin in wool is stripped out and used in other industries, but enough remains in the wool that it retains its hydrophobic properties. While wool does absorb water, the lanolin moves that water to the outside of the garment, keeping the inside relatively dry. Additionally, wool does not lose its insulating properties when it gets wet. That alone makes it valuable for outdoorsmen, especially for fly fishers who fish in cold water and for hikers and campers who go out in winter.
Advantages of Cotton
If you’re wearing cotton clothing on your outdoor adventures, you likely chose it because it was exceedingly comfortable and soft, or because it breathes well.
Cotton is always going to be quite soft. Even roughly-woven cotton, like cotton canvas or cotton duck, will be softer than comparable fabrics made of other materials, because cotton fibers are smooth and pliable. As cotton fabric moves and ages, it only gets softer. This is because, over time, a tiny amount of the cotton fiber will fluff out from the surface of the fabric. This microscopic fluffiness is what makes cotton so soft and comfortable. When making some fabrics, like flannel, the cotton thread is combed before weaving to intentionally fluff it up. Think about the soft fuzzy surface of your favorite flannel shirt, and you’ll know exactly what that means.
Cotton is also very breathable. Breathability means that humid air flows easily through cotton and prevents hot air from being trapped near your body. This breathability comes from the shape of the cotton fibers themselves. When you look at an individual cotton fiber under a microscope, it isn’t a perfectly straight line; instead, the fibers resemble twisted ribbons. This creates tiny open spaces for air to pass through when the fibers are woven into fabric. Layers of cotton can trap the air and add insulation, but a single layer of cotton won’t trap heat. In the summer, that’s exactly what you’re looking for.
Wool Vs Cotton
So how do wool and cotton compare when we put them head to head? Here’s how the two compare to each other when we look at different scenarios.
Wool will always win in the battle of insulation, due to the way that wool fabric is formed. Those overlapping scales on the shafts of the fiber are perfectly made to trap air and keep it close to the body. This means that in cold weather, wool can protect you from hypothermia and keep your body temperature up. Wool also retains its insulating properties when it gets wet– this is why cold-climate outdoorsman almost always wear wool layers. Cotton can be an insulator when worn in layers, but when it gets wet, it loses all of its insulating properties.
Wool is hydrophobic; cotton is hydrophilic. Where wool wicks away moisture, cotton absorbs it. And unlike wool, which moves the water from the inside to the outside, when cotton gets wet… it stays wet. Cotton gets saturated with water whenever it gets wet, whether that water is mist or rain, or the sweat from your body. In summer, when it’s hot, the heat evaporates the water you sweat into cotton, which helps keep you cool. But if you’re wearing cotton in the cold or the rain, that trapped water just cools down and can make you a lot colder. If you’ve ever heard the phrase “Cotton kills,” this is why– wearing it in inappropriate scenarios can lead to hypothermia. So don’t wear cotton in the rain, or in outdoor scenarios where you may get wet!
Both cotton and wool are renewable resources. However, cotton is known as a “thirsty” crop, which means that it takes more irrigation than comparable crops. Wool, which comes from sheep (an animal that first evolved in the desert), actually requires less water pound-for-pound than cotton.
Cotton also uses petrochemicals and pesticides when grown conventionally, and sheep produce a lot of methane, which contributes to the greenhouse effect. Neither one is perfect; however, when you compare the impact of cotton and wool to synthetic fabrics, either one is a much better choice. If you want the most eco-friendly, sustainable fabric possible, choose organic cotton or alpaca wool. Alpacas produce less methane and use even less water than sheep do.
Cotton is always going to be cheaper than wool (at the same quality). Wool is more expensive to produce than cotton, both at the fiber stage and the cloth-making stage. However, cotton has different price ranges– not all cotton is as expensive as the luxury Pima cotton or organic cotton. There are lots of other factors that go into the price of a garment, bag, or other pieces of gear, too– and usually, when you’re choosing between cotton and wool, one of them is going to be more appropriate for your situation than the other. It’s the factors that make them appropriate for any given scenario, like breathability, insulation, or water resistance that will likely be the deciding factor in your purchase.
There’s a reason we don’t make our t-shirts out of wool; it’s itchy! Wool fibers can be highly uncomfortable when worn next to the skin. Some people even have an allergic reaction to it– usually due to the lanolin content. Cotton, on the other hand, is extremely soft. Many soft fabrics, like flannel, chenille, and even velvet are made out of cotton that’s been carefully woven. Pima cotton and Egyptian cotton are two special kinds of cotton that have longer fibers and are harvested by hand to prevent damage to these fibers, so things made from these materials are usually softer and more comfortable than other kinds of cotton. Egyptian cotton is super popular for bedding, while Pima cotton makes some of the softest t-shirts ever.
Wool is much heavier than cotton. While both fibers can be woven into heavy and light fabric, wool is significantly denser. Also, wool is made up of protein and lipids– keratin and lanolin– while cotton’s chemical structure is a carbohydrate– cellulose, which is a much lighter material. Wool also has layers surrounding a core within its fibers, which cotton does not have. That means there’s more to a wool fiber, so of course, it’ll weigh more than cotton fiber. Inch for inch, wool is just a heavier fiber! This means that it’s great for heavy blankets, sweaters, and other cold-weather gear.
Both cotton and wool are naturally odor-resistant, but wool is more odor-resistant than cotton. This is due to its structure- those overlapping scales on the fibers create channels that move dirt and debris to the outside. It doesn’t need to be cleaned as frequently as cotton does, and is even antimicrobial thanks to the lanolin and scale structure. But either fabric won’t retain odors, especially when properly cared for and laundered.
Cotton beats wool here, and this can be a good thing or a bad thing depending on the climate. If you’re in a cold area, you might not want your fabric to breathe- that means that it’s letting that cold air in and isn’t regulating your skin temperature appropriately! But on a hot day, nothing beats cool, breathable fabric.
There is one variety of wool, Merino, that is suitable for summer clothing. Merino’s long, fine fibers can be spun and woven into lightweight fabrics that are used as activewear– think Merino socks. When the fiber is lightly woven, it still wicks away moisture but doesn’t insulate as effectively. So you won’t get too hot if you wear Merino socks under your hiking boots in the summer.
Washing Wool and Cotton
Both wool and cotton are odor and dirt-resistant and don’t need to be laundered as frequently as synthetic fabrics. When you’re washing cotton clothes, it’s best to do so in cold water– especially when they’re brand new, to avoid shrinkage. Over time, the cotton fibers will lose some of their tension and go a bit more slack– at this point, your cotton clothes won’t shrink.
Wool is a little bit more delicate to wash because too much hot water and agitation will shrink and felt the fabric, which you don’t want. To wash wool, turn the garment inside-out and use a gentle detergent made for wool, like Woolite. Make sure that your washer is on the gentlest cycle, and only use cold water.
You should never put wool in the dryer– even without heat, tumble drying can turn the fabric into felt. Instead, air-dry your wool clothes and blankets. When in doubt, you can spot-clean bigger wool items like blankets. Since wool is odor-resistant, it doesn’t need to be washed as frequently– but you’ll probably still want to wash your wool socks pretty regularly!
When To Choose Wool Vs Cotton
- If you’re outside in the summer, where you know it won’t be rainy? Cotton.
- If you’re doing outdoor activities where it’s cold and wet? Wool.
- If you’re buying sheets? Cotton.
- If you’re buying a winter blanket? Wool.
- If you’re buying underwear? Cotton.
- If you’re buying a coat? Wool.
Both wool and cotton are awesome fibers that make amazing fabrics. Both are durable and can make great outdoor gear. But you need to make the right choice for your safety and comfort!
Max DesMarais is the founder of Hiking & Fishing. He has a passion for the outdoors and making outdoor education and adventure more accessible. Max is a published author for various outdoor and marketing websites. He is an experienced hiker, backpacker, fly fisherman, trail runner, and spends his free time in the outdoors. These adventures allow him to test gear, learn new skills, and experience new places so that he can educate others. You can read more about him here: hikingandfishing/about