It's not just friction — it's shear. Podiatrist Rebecca Rushton's research points to something more specific than simple rubbing: shear, where layers of skin move in opposite directions against each other. Moisture and heat don't cause blisters directly — they soften the skin and increase friction, which makes shear injuries far more likely. A sock that shifts, bunches, or slips inside your boot as you walk is constantly generating that shear — and a damp sock makes the skin more vulnerable to it.
Cotton is the biggest culprit. Cotton absorbs sweat and holds it against the skin instead of moving it away. Wet skin is softer and more prone to friction damage, which is exactly why hiking guides universally warn against cotton socks — REI states it plainly: “avoid cotton, which retains moisture.”
Fit matters as much as fabric. A sock that's too loose bunches and creates pressure points; too tight, and it restricts circulation and creates its own hot spots. The British Mountaineering Council notes that even military studies on blister prevention consistently point back to sock choice and fit as a primary controllable factor.
Height matters too — more than most people realise. A sock that ends mid-calf, below where your boot cuff sits, leaves a gap where the top edge of the boot rubs directly against bare skin with every step. That's a classic, avoidable hot spot. A sock that extends further up the leg — like ours does, just below the knee — puts a layer of moisture-wicking fabric exactly where boots tend to create friction.
The fix, in practice:
- Choose a fibre that actively wicks moisture away from skin rather than holding it there — alpaca absorbs only around 10-11% of its weight in moisture and dries fast, keeping skin drier for longer.
- Get the fit right — snug enough that the sock doesn't shift inside the boot, without cutting off circulation.
- Cover the zone where your boot meets your leg, not just your foot — height reduces skin-on-boot contact at the cuff.
- Change socks partway through a long day if your feet run hot or wet — REI recommends this as a simple, effective habit.
None of this is about buying a “miracle” sock — it's about removing the two conditions blisters need most: moisture and movement. Get the fibre and the fit right, and most blister problems disappear before they start.
Which anti-blister socks to choose
Applying all of the above, here is what we would reach for and why.
- Long walks and hill days — Alpaca Boot Socks. Height above the boot cuff, 74% alpaca to move moisture out, plus nylon and spandex so the sock holds its shape instead of shifting and shearing.
- Walking boots in milder weather — Merino Boot Sock, or the Merino Boot Sock Bundle, which gives you the spare pair to change into partway through.
- Trail shoes and lighter days — Alpaca Crew Socks.
- Work boots and long shifts — the work collection, built for the same problem over a different day.
Browse the full walking collection to compare heights and weights. And whatever you choose, buy two pairs rather than one — changing socks halfway through a long day does more for blisters than any single clever feature.
SOURCES
- How to Prevent and Treat Blisters While Hiking, Hiking Insights — hikinginsights.com
- How to Prevent & Treat Blisters, REI Expert Advice — rei.com
- Friction Blisters: Prevention and Treatment, British Mountaineering Council — thebmc.co.uk
- Alpaca Fiber vs. Merino, Cotton & Synthetics, Warrior Alpaca Socks — warrioralpacasocks.com
