In the past few years, a new fabric has become popular called Coolmax. It’s mainly used in sports apparel, but some sock manufacturers have also started using it in their sock models, including Darn Tough, Injinji, REI Co-op, and Fox River.
But are socks made from Coolmax really good enough to be used as an alternative to merino wool hiking socks? In this article, I’ll explain what are the benefits and drawbacks of Coolmax socks, in what situations they’re good, and in what not.
What Is Coolmax And Why It’s Used In Hiking Socks
Coolmax is a synthetic fabric made from 100% polyester, trademarked by the same company that makes Lycra and Neoprene – DuPont. Its main difference from polyester is that each yarn is stretched in a certain way to turn it from a round yarn to a rectangular one with multiple grooves in the middle. Coolmax is marketed as a breathable, quick-drying, and moisture-wicking fabric, which is perfect to use for sports apparel.
I looked for different studies online on how it compares to polyester and wool, and I found a study that does indeed confirm that Coolmax is more moisture-wicking and quicker drying than polyester and wool. Another study also confirmed that Coolmax is more breathable in dry and vapor permeability than wool. So from what I could find, its marketed features do indeed check out (if we assume that these tests were done correctly).
Benefits Of Coolmax Hiking Socks
- Dries very quickly. Coolmax is made from polyester, which absorbs only less than 1% of its dry weight in water (for context, wool can absorb up to 35%). This means that the fabric can also dry very quickly because when it’s wet, it stores much less water inside. Coolmax socks usually dry 2x quicker compared to merino wool.
- Very breathable. Coolmax socks are especially useful for people whose feet sweat excessively in merino wool socks because it’s even more breathable than wool (which is very breathable by itself). This makes them an ideal choice for summer hiking.
- Durable. Although Coolmax is a bit less durable than nylon, it’s still much more durable than wool. This means that socks made from Coolmax will develop holes slower than wool ones.
- Good compression due to a stronger fabric. Coolmax, just like most other synthetics, is a fairly strong fabric, which doesn’t stretch out over time. When combined with elastane or spandex, these socks will provide a very snug fit.
- Can be made into a very thin fabric. Because it’s a synthetic material, its yarns can be much thinner than natural wool fibers, which means that they can be weaved into a thinner fabric. This is useful for the manufacturing of sock liners and ultra-lightweight hiking socks.
- The best vegan alternative to wool. Coolmax isn’t as good as wool, but it’s the next best 100% synthetic fabric due to its impressive breathability and moisture-wicking properties. When Coolmax is combined with acrylic, nylon, and elastane or spandex, a rather good hiking sock can be created, which is almost as good as merino wool.
Negatives Of Coolmax Hiking Socks
- Absorbs smelly odors very quickly. Polyester naturally absorbs oils, and because Coolmax is made from polyester, it has the same characteristic. All the natural oils from your sweat are absorbed by this material, and the fabric starts to smell very quickly. This is the main downside to Coolmax socks, as it’s the one that people complain the most about. Wool, for example, has antimicrobial properties, which help with odor resistance. From my own experience, merino wool socks smell fresh at least 2x longer (closer to 3-5x) than Coolmax ones.
- Over time, feet get wet quicker compared to wool. Even though Coolmax is moisture-wicking and breathable, it can’t absorb a lot of water. Wool can absorb sweat inside the fabric and slowly release it over time through the exterior layers, whereas Coolmax will reach its threshold rather quickly, and then any excess sweat will start to accumulate on your skin. You won’t feel this on short day hikes or when trail running, but you will when walking for long distances every day.
- Not ideal for winter hiking due to poor insulation properties. Coolmax is really only meant for summer hiking due to its breathability and moisture-wicking properties. It can be combined with acrylic or polypropylene to create winter socks with rather good insulation properties, but it will never beat wool socks, which are much warmer.
What Situations Coolmax Hiking Socks Are Good For
Coolmax hiking socks are the ideal choice for vegans, who don’t wear wool and other animal-made products, or people who are allergic to wool. When combined with acrylic, nylon, and elastane, a sock of similar properties to merino wool is made, which will be good for all-year-round hiking.
Another situation where Coolmax socks excel is trail running and day hiking in hot weather. That’s because these socks are thinner, more breathable, and more moisture-wicking than merino wool socks. So in the short term, they will keep your feet cooler.
When Using Merino Wool Hiking Socks Is A Better Option
Although Coolmax socks aren’t bad, merino wool socks are pretty much always better, even in hot weather hiking. That’s because merino wool has excellent thermoregulation properties, which essentially allow your feet to stay cool in the summer and warm in the winter. In addition to that, your feet will pretty much always stay dry.
In summer hiking, thin merino wool socks will outperform thin Coolmax socks when walking for longer periods, because Coolmax can keep your feet dry and cool only for a few hours of active hiking, whereas wool can do that for the whole day. Merino wool is also antibacterial, so merino wool socks will smell fresh for much longer.
The only downside to wool is that it dries much slower than Coolmax and is less durable. However, when merino wool is combined with nylon and elastane, the fabric becomes much more durable, stretchy, and water-resistant, giving it the perfect properties for a hiking sock.
Read Next: What’s the Best Material for Hiking Socks?
Frequently Asked Questions About Coolmax Hiking Socks
What are the best Coolmax hiking socks?
In my opinion, the best Coolmax socks for hiking are made by Darnn Tough. The Darn Tough Coolmax Micro Crew Cushion is a really good option for most hikes in the spring, summer, and autumn. They’re made from 55% Coolmax, 37% nylon, 5% acrylic, and 3% Lycra. This combination gives the best amount of breathability, moisture-wicking, durability, warmth, and fit. They’re perfectly suited for shorter hikes and everyday use, but they can even be used for long-distance hiking, although the Darn Tough Micro Crew Cushion Merino Wool socks are a slightly better option, as you’ll be dealing with fewer blisters.
Are Coolmax socks also suitable for winter hiking?
Coolmax socks aren’t ideal for winter hiking. That’s because Coolmax is designed to be breathable and moisture-wicking, rather than insulating. Only when Coolmax is combined with acrylic or polypropylene, the fabric becomes insulating enough to be used in colder temperatures. But even then, merino wool socks will pretty much always outperform purely synthetic socks due to Merino wool’s excellent thermoregulation and insulation properties.
Are 100% Coolmax socks suitable for hiking?
100% Coolmax socks (or 95-99% mixed with a bit of elastane, spandex, or Lycra) aren’t really great for hiking longer distances. They’ll do fine on short hikes, and they’re a much better choice than any cotton sock. But when walking longer distances, your feet will become slightly damp and develop blisters. Plus, 100% Coolmax socks will also start to smell bad really quickly because Coolmax absorbs oils.