Footwear

Hydrocolloid Dressing

Also called hydrocolloid blister pad, gel blister plaster, blister gel pad

What is a hydrocolloid blister dressing?

A hydrocolloid dressing is an adhesive pad with a gel-forming layer that seals over a blister or small wound. It absorbs fluid, cushions the spot and keeps dirt out, and it is meant to stay on for days until it comes off by itself.

What it is: Adhesive pad with a gel-forming layer
Best used on: A formed or torn blister
Wear time: Several days; Until it lifts by itself
Common makers: Compeed, Band-Aid

How does a hydrocolloid dressing work on a blister?

The pad's inner layer contains gel-forming particles. As it takes up fluid from the blister, that layer swells into a soft gel, which is why the pad turns white or puffy over the spot after a day or so. The bump is a sign it's working.

The outer film keeps water and grit out, and the gel cushions the spot so a boot presses on padding rather than raw skin. Compeed and Band-Aid's blister bandages are both hydrocolloid pads.

When should a hiker use one?

Use one once a blister has formed, and especially once it has torn open. That is broken skin, and the American Academy of Dermatology's advice is to keep it clean and covered. Before that stage, at the hot spot, tape or moleskin is the better choice, because they take friction off skin that is still intact.

Clean and dry the skin first, warm the pad in your hands for a few seconds so it molds to the curve of a heel, and press the edges down.

How long do you leave it on?

Leave it until it starts to come off on its own, which makers put at several days. Pulling one off early to check underneath can tear the roof off the blister, which is the skin protecting it. If the edges start to roll in a sock, trim them or cover them with a strip of tape rather than replacing the pad.

What this means when you're choosing

Mixed sizes, since heels, toes and the ball of the foot need different shapes
Thin, tapered edges that won't catch on a sock
Individually sealed pads, so the rest stay clean in a kit
Enough of them: one blister can use two or three pads on a long trip

Hydrocolloid Dressing vs Moleskin

	Hydrocolloid Dressing	Moleskin
Best moment	A blister that has formed or torn open	A hot spot, or padding around an intact blister
Where it goes	Directly over the blister	Over a hot spot, or cut into a ring around a blister
What it does	Seals, absorbs fluid and cushions	Pads and takes friction off the skin
Staying power	Designed to stay on for days	Can lift at the edges in a wet boot

Which to pick: Moleskin is for the stage before the skin breaks; a hydrocolloid dressing is for after. Most blister-prone hikers carry both.

The common mistake

Peeling it off to look

The white bubble under the pad looks alarming, and the urge is to pull it off and check. Doing that can take the blister's roof with it and leave raw skin in a boot. Leave it alone until it lifts by itself.

Common questions

Can you put a hydrocolloid pad on an unpopped blister?

Yes. It cushions and protects an intact blister as well as a torn one. The thing to avoid is peeling it off early, which can tear the blister open.

Why did my blister pad turn white?

The gel layer has absorbed fluid from the blister and swollen. That's the dressing doing its job.

Where this is defined

How to prevent and treat blisters, American Academy of Dermatology

Where this comes up

Guides on Tom's Hiking where hydrocolloid dressing changes which product is right for you.

More in footwear

Lug depth

Lugs are the raised blocks on the sole of a boot or trail shoe, and lug depth is how tall they are, usually 3 to 6 mm. Deeper lugs bite into soft ground; shallower ones give more contact area on rock and hard trail.

Outsole

The outsole is the rubber layer on the bottom of a shoe, the part touching the ground. It carries the lug pattern and the rubber compound, which together decide grip, and it's usually the first part of a shoe to wear out visibly.

Midsole

The midsole is the foam layer between the outsole and your foot. It absorbs impact and sets how stiff or soft a shoe feels, and it's the part that quietly dies long before the tread looks worn.

EVA foam

EVA is the light, springy foam most hiking and running midsoles are made of. It cushions well and weighs little, but it compresses permanently over time, which is why shoes go flat after a few hundred miles.

Stack height

Stack height is how much material sits between your foot and the ground, measured in millimetres at the heel and forefoot. More stack means more cushioning and less ground feel; less means more feedback and a lower, more stable platform.

Heel-to-toe drop

Drop is the height difference between a shoe's heel stack and its forefoot stack, given in millimetres. Zero drop means the foot sits level; 8 to 12 mm tilts you forward slightly and shortens the load on the calf and Achilles.

Rock plate

A rock plate is a thin stiff sheet, usually TPU or a nylon composite, embedded in the forefoot of a shoe. It spreads the load from a sharp rock across the whole foot instead of letting it press into one point.

Shank

A shank is a stiffening insert running through the arch of a boot, made of steel, nylon or composite. It controls how much the boot twists and bends, which is what lets a boot support a heavy load and edge on rock.

Rand

A rand is a strip of rubber bonded around the lower edge of a boot's upper, most often at the toe. It takes the abrasion from rock and roots that would otherwise wear through fabric or leather, and it protects your toes from impact.

Toe cap

A toe cap is the reinforced bumper, usually rubber, over the front of a hiking shoe or boot. It shields your toes when you kick a rock or a root, and it keeps the upper from wearing through at the spot that scuffs the ground most.

Gusseted tongue

A gusseted tongue is sewn to the sides of the boot with fabric panels instead of hanging free. It seals the gap along the laces so grit and water can't get in, and it stops the tongue sliding sideways as you walk.

Vibram Megagrip

Megagrip is a Vibram rubber compound formulated for grip on wet and dry rock. It's softer and stickier than standard hiking rubber, which is why it holds on slabs and greasy roots, and why it wears out faster.

Gaiters

Gaiters are fabric sleeves worn over the top of a shoe or boot to keep grit, snow and water out. Low trail gaiters cover the collar and stop scree filling your shoes; tall gaiters run to the knee and seal the leg against deep snow and wet brush.

Microspikes

Microspikes are elastomer harnesses with short chains and spikes, roughly 10 to 15 mm, that stretch over a shoe for traction on packed snow and ice. They are the middle rung between yaktrax-style coils and full crampons, and they are not mountaineering equipment.

Crampon

A crampon is a metal frame carrying 10 or more points up to 5 cm long that binds rigidly to a stiff-soled boot, so a climber can stand on hard alpine ice and steep snow. It is the tier above microspikes, and it is technical equipment that needs an ice axe and training.

Insulation weight in grams

Insulation weight is the mass in grams of one square meter of the insulating sheet inside a boot or glove. A 400g boot uses a heavier sheet than a 200g boot, so it is warmer, but it is nothing like twice as warm.

Vibram Arctic Grip

Arctic Grip is a Vibram outsole technology built for traction on wet ice. It stays pliable at temperatures where ordinary hiking rubber goes hard, which is the reason a winter sole grips where a three season one skates.

Flotation

Flotation is how well a snowshoe keeps you on top of snow instead of sinking into it. It is a function of deck surface area measured against your loaded weight, which is your body plus clothing, boots and everything in your pack.

Heel lift

A heel lift is a small wire or plastic bar behind the heel of a snowshoe that flips up so your boot rests on it during a climb. It stops your calf being held at full stretch on sustained steep ground.

Heel counter

A heel counter is the stiffened section at the back of a shoe or boot that wraps around and holds your heel. It keeps the heel from sliding and rolling inside the shoe, which is where both stability on uneven ground and a blister-free heel start.

Heel cup

A heel cup is the raised, curved wall around the back of an insole that cradles your heel. A deep, firm one centers the fat pad under the heel bone and stops the heel sliding inside the boot, which is most of what a supportive insole does for stability.

Footbed

A footbed is the cushioned, usually removable layer your foot rests on inside a shoe or boot, and what most people call the insole. Stock footbeds are typically inexpensive fillers, and replacing one with a supportive aftermarket insole is the cheapest way to change how a boot fits.

Huarache

A huarache is a minimal sandal built from a thin flat sole and a lace or strap that passes through a hole between the big and second toes. Modern running and hiking versions copy the sandals worn by the Raramuri of Mexico's Copper Canyon.

Moleskin

Moleskin is a soft, thick cotton pad with an adhesive back that you stick over a hot spot so it takes the rubbing a blister would otherwise take. Once a blister has formed, it is cut into a ring and placed around the blister rather than on it.

Liner sock

A liner sock is a thin, close-fitting sock worn under a hiking sock. When the foot moves inside the shoe, the two sock layers slide against each other instead of the outer sock sliding against skin, and the liner also wicks sweat outward to the thicker sock.

By Tom · Last reviewed October 30, 2026. Back to the glossary