Friction, too much friction | What's the key to socks that prevent blisters?

Reducing hot spots, blisters and irritation on our feet is crucial, not just when you are running or hiking but throughout the day, in business shoes, work boots or your casual kicks.

With the main function of a sock being to act as a barrier between your skin and a shoe to protect it from scrapes, pressure and blisters, it's important to choose right. Do you need material that is moisture loving or not? Should your socks be thick or thin? Is wool too warm for hot weather? We're going to delve in to answer these and maybe bust a few pre-conceptions.

Getting blisters or hot sports is highly influenced by the fabric composition of the socks you wear. This is because different sock fibers, have differing friction coefficients, which basically means how much friction or resistance the fiber creates.

To add complicate it a little further, the friction characteristics change based in different conditions and when your socks get wet or sweaty, certain fiber can really excel. So let's have a quick look at what the key fiber's are in socks that prevent blisters.

Friction, too much friction

The key is to reduce friction. less friction means less red skin and blisters.

Cotton:

Cotton is a very sustainable fiber but for socks, particularly sports socks, has high friction and tends to deform and pill as it dries, leading to blisters and the sock often becoming stiff and losing shape. This is why you usually only see cotton used in casual socks.

Acrylic:

Acrylic fibers have shown to have the highest frictional forces under all conditions. Acrylic is a time of fiber made from plastic polymer fibers similar to nylon, polyamide, coolmax etc. Pertroleum based fibers such as these are often the material of choice for a lot of sports socks due to their moisture wicking and hydrophobic (doesn't absorb moisture) properties, but they seem to have greater friction as well as more fabric deformation when wet.

Wool:

Fine wool has less frictional force that acrylic fibers

When comparing acrylic fibers to wool, wool has significantly less frictional force and in a lot of research is a clear favourite. (1,2)

This is summed up nicely in a research paper done at Otago University (Van Amber et al., 2014) that looked into the effect of fiber type of frictional characteristics in socks:

"The most important effect of fiber was on the static frictional force and coefficient of static friction of damp fabrics, with fabrics composed of fine wool exhibiting lowest friction, and acrylic fabrics the highest."

Weight:

Heavier weight socks lead to about double the frictional force of light weight socks, irrelevant of the fiber type in your sock. The key is not to aim for a super thick sock but a sock with high quality fibers with low friction that form a thin membrane over your skin.

Moisture:

You can group sock fibers into two groups.

1. Hydrophobic Fibers, which do not absorb much moisture, which means excess moisture is drawn through the fabric and can then be wicked away but it doesn't absorb it off the feet and due to the moisture repelling hydrophobic properties, tends to only wick away excess. The main fibers you know that do this is your plastic fibers such as polyamide and CoolMax.

2. Hydrophilic Fibers, which absorb moisture. Examples of this are cotton and wool. There is a difference between these two fibers though as wool has some intricacies that help sheep adapt to various temperatures and conditions.

Merino wool actually has a hydrophobic outer that repels water and a hydrophilic (moisture loving) inner which absorbs water vapor. This moisture absorbing cortex can absorb up to 1/3 of it's weight while still feeling dry on your skin. This all means that this super fiber can absorb a heap of perspiration while also feeling drier than other fibers due to it's hydrophobic, dry, other later.(3,4)

This great wicking ability of wool makes wool socks not just ideal for cold temperatures but also ideal for warm temperatures too!

Conclusion:

Fine wool fiber and yarn creates less friction and so helps to reduce the incidence of blisters. When the fabric is wet, it performs even better when compared to acrylic type fibers and is also less likely to deform. For reducing blisters and avoiding too much friction, chose socks with merino wool that form slim, membrane like protection over your feet. For EVEN MORE blister protection, choose toe socks, which wrap each separate toe in a protective membrane.

Why are our socks a blend, not 100% merino?

We chose to commit to having at least 50% of our composition made with Merino yarn. Other than the sustainability aspect of using a renewable fiber, our main priority was performance and keeping you comfortable and blister free all day, whether you're battling hot muggy conditions, cold and wet weather or dry heat.

We found  a blend of fibers gets the best of both worlds. Fine merino yarn for moisture and temperature regulation, reduced deformation and less friction but also polyamide (nylon) for strength and resilience and spandex for further elasticity and reduced slippage. Research has also shown that a blend with 50% merino was best over a long hike as well as showing that when compared to socks with no wool, they had more dry spots, and stored about 3 times more moisture.