To understand fiber choices for climbing socks, it’s important to first understand what makes a good climbing sock. You can read my full breakdown of “What Makes Performance Climbing Socks Different” here.
In short, the key features to look out for are fit, thinness, moisture management, and friction. Today I want to look at each of these features from the perspective of popular sock fibers to help climbers understand why GraceWül climbing socks are the top choice in the sport.
Climbing Sock Fit
The fit of climbing socks is important. Climbers need a sock that feels like going barefoot: essentially a second skin for your feet. Though the fit of climbing socks mainly comes down to construction, fiber does a play a role.
Polyester and Nylon are synthetic fibers, essentially a plastic of some form, as such it does not have any inherent elasticity and would rely solely on added elastic to first stretch to your foot and then form to it. On the plus side, since it does not stretch or shrink, you would not have to worry about it getting stretched out and becoming too loose over time.
This is the main fit problem with cotton. As a natural fiber it naturally has stretch and initial shrinkage. It can stretch on and form to your foot… at first. However, though cotton has initial shrinkage with washing, it does not have much shrinkage or bounce back after that. This means that a cotton sock will continue to stretch slightly with use, but does not regain it’s shape with washing, moisture, heat, etc.
Wool is also a natural fiber. Like cotton it has stretch and initial shrinkage. Unlike cotton, it is a naturally springy, lofty fiber. This allows it to bounce back to shape after being stretched. In the short term, it helps climbing socks form to your foot. In the long term, if it does get stretched and loose from wear, it will bounce back to shape with washing. Even before washing, the moisture and warmth of your foot will help it maintain shape during use.
Thin Socks for Climbing Shoes
I talk a bit about why thinness matters in my “Best Socks for Climbing Shoes” post. Climbers need a sock that they can barely feel and fits in their super tight, often down sized climbing shoes. Regular socks are too thick, they either won’t fit, won’t fit comfortably, or creates a layer that messes with the sensitivity of touch. Again, the knit construction of the sock plays a role in this feature. But so does the structure of the yarn, which is made of fibers. This can get confusing, so let me try to break it down simply.
Socks are made of yarn, yarn is made of fibers. It’s a multi level construction, with each layer having a choice of thickness/thinness. A thin sock has to be made with a thin yarn, which has to be made of thin fibers.
Cotton and Wool are staple, or short fibers. This means that wool and cotton yarn always has to be made by overlapping and spinning several fibers together. The longer the fiber, the less overlap is needed and the thinner a yarn can be. Specialty breeds of sheep are long haired, meaning they are going to have longer fibers than cotton and other wool, making it possible for a thinner yarn.
Polyester and nylon are synthetic. They are created by using a melted plastic based solution and extruding it into long filaments fibers (or long continuous strings). Though these continuous strings could be used on their own as a yarn, that would create a strong plastic feel with an unbreathable attribute to them. Because of this these long fibers are typically cut into shorter fibers and spun together into a yarn to mimic a natural feel. The advantage is they can be created very thin, and cut into fibers longer than wool. This gives a thin option, but with the trade off of breathability and feel.
Moisture Wicking Climbing Socks
In my post “How to make Climbing Shoes Last Longer” I talk a good deal on moisture management and sweating in shoes. Moisture wicking for performance socks takes place almost exclusively at the fiber level.
Cotton is a fiber that gets wet quick and stays wet for a while. What this means for climbing socks is that it will soak up the sweat from your feet quickly. However, it will quickly be soaked through and sit in your shoe and against your skin for the remainder of your session.
Wool is a hydrophobic fiber, this gives it water repellent attributes. It will not soak up moisture as quickly as cotton, but it will work to repel it, or dry itself when it does. This is what gives it natural moisture wicking properties.
Polyester, as a form of plastic, has zero ability to absorb moisture. This is why a polyester or nylon sock will almost always feel dry. However, it usually also means your foot stays wet. Some textile manufacturers have found ways to using the structure of polyester when extruded to have moisture wicking channels in the fiber that helps move moisture around, wicking it away from your feet.
Friction Grip in Climbing Socks
A frictional component is necessary for climbing socks to lock in and grip the inside of your shoes, preventing slipping during pivotal moments, such as heel hooks.
Cotton is a smooth fiber with little to no friction. It relies on added silicone grip pads, creating extra bulk and pressure points.
Wool is a crimped fiber, made of tiny external barbs along the length of the fiber. These barbs acts as tiny hooks while the crimp creates extras surface area and roughness causing friction against the shoe and your foot.
Polyester and Nylon as filament fibers are typically smooth. However, as extruded fibers, it can be created in a variety of shapes and structures. (Think extruding play dough through different shaped holes as a child). This can allow for high friction threads to be manufactured that inherently grip and stick to your shoes and feet while climbing.
