Blisters are a friction problem, not a toughness problem

The options around blister prevention are set out side by side below, with the conditions that genuinely favour one over the other.

The mechanism is shear

A blister forms when layers of skin slide against each other repeatedly, tearing them apart and filling the gap with fluid. Pressure alone does not do it; movement does, which is why a tight boot rubs less than a loose one. This is why the fix is stopping the movement rather than toughening the surface.

The fluid that fills the gap is the response rather than the injury, a sterile cushion protecting the raw layer beneath while it regenerates, which is the whole reason an intact blister heals faster than a burst one.

Moisture is the multiplier

Wet skin is weaker and has a higher coefficient of friction, so the same rubbing does far more damage. Sweat is usually the culprit rather than rain, which is why blisters happen in summer as often as in wet weather.

On the ground, socks that move moisture, and a sock change at lunch, do more than most people expect. Reducing the sweat itself is the other lever, and some walkers get useful results from applying an antiperspirant to the feet for several nights before a trip, though the evidence is mixed and it irritates the skin of a minority.

Three ways to reduce friction

Remove the movement by fitting the shoe properly and lacing it so the heel is held. Reduce the friction with tape on known problem spots, applied before walking rather than after. Move the friction into a sacrificial layer, which is the argument for a thin liner sock under a thicker one.

None of the three excludes the others, and people who blister reliably usually end up doing all of them at once: a shoe laced to hold the heel, tape on the two spots that always go, and a liner under the main sock.

Act on the hot spot

A hot spot is the warning that arrives an hour before the skin gives way, and it is the moment to stop. Taking boots off, drying the foot and applying tape takes two minutes at that stage. People who finish long walks are, almost without exception, people who stop when they feel it.

Locally, taping badly makes it worse, because a wrinkle or a short edge inside a shoe becomes a new pressure point in its own right, so the tape has to go on smooth, onto dry skin, and extend well beyond the area that hurts.

If one forms anyway

Small intact blisters are generally left alone and covered; large ones under pressure are often drained at the edge with a sterile point and left roofed. The skin over the top is the best dressing available, and removing it invites infection. Signs of infection — spreading redness, heat, pus — need medical attention rather than more tape.

Over a season, where the roof has already gone, the aim is a clean non-adherent dressing with padding built up around the edge rather than pressed on top, and hydrocolloid dressings do that well provided they go onto clean skin and are then left alone.

Where the blister is tells you what to change

A heel blister means the heel is lifting inside the shoe, which is a lacing and fit problem rather than a sock problem. Blisters on the ends of the toes come almost entirely from descending in a shoe that has become too short once the foot swelled, and no amount of tape adds length.

Blisters between the toes point at moisture and seams, and are the one location where toe socks or a smear of lubricant genuinely outperform taping. Feet swell across a walking day and further across a long trip, so a shoe fitted first thing in a shop is being tried on the smallest foot you will ever have.

Side by side

The takeaway

Stop at the hot spot. Everything after that point is damage control.

What holds up over a week outdoors is rarely what looks best at the trailhead.