The technology
How waterproof socks work
“Waterproof” is a word anyone can print on a label. This is what’s underneath ours, so you can judge it rather than take our word for it.
The waterproof layer
Porelle® isn’t a name we made up
The waterproof layer is Porelle®, made by a separate company. That matters more than it sounds: a named layer is one someone else has to stand behind, and you can go and look them up. Water can’t get through it. Sweat, as vapour, can.
Brands that don’t name their waterproof layer are asking you to trust an unnamed one. We’d rather you checked ours.
The principle isn’t new and isn’t ours. A waterproof breathable layer works because liquid water and water vapour are very different sizes. The holes are far too small for a droplet to pass through and comfortably big for a vapour molecule. That difference is the whole technology, and it’s been in outdoor clothing for decades.
The build
Why there are three layers
One waterproof layer on its own would be uncomfortable and wouldn’t last. The other two exist to make it wearable.
The layer doing the waterproofing is the one you never touch. That’s deliberate — a waterproof layer exposed to rubbing is a waterproof layer with a short life.
Inner layer
Against your skin
A soft knitted lining that moves sweat off your foot and keeps the waterproof layer from sitting directly against you. Without it a waterproof sock feels like a carrier bag, and the layer wears out against your foot instead of against the shoe.
This is where most waterproof sock pages go vague. It’s also the question nearly everyone actually has, so here’s the mechanism and the limit.
Breathability is a rate, not a state
The layer moves sweat outwards at a certain speed. It doesn’t remove moisture and it doesn’t make a sock ventilated.
Where the limit is
Your foot produces sweat at a rate that depends on effort and temperature. Produce it faster than the layer can move it and the surplus stays inside. That isn’t a fault, it’s arithmetic.
When you’ll notice
Walking pace in British weather is comfortably within it. A steep climb in mild air, a hard run, or summer rain will exceed it. Cold air helps, because the difference in humidity across the layer is what drives it out.
What actually helps
A sock that fits, footwear that isn’t sealed shut, and taking them off at the end of the day. No waterproof layer changes the fact that a foot in a boot for ten hours is in a humid place.
Testing
We don’t publish test figures yet
Independent test data is the only kind worth printing and we don’t have it yet. Rather than quote a waterproof rating or a breathability number we can’t stand behind, we’ve left this section empty until we can.
For what it’s worth, the two numbers to ask any brand in this category for are hydrostatic head — how much water pressure a fabric holds back before it leaks — and a breathability rating, usually given as grams of vapour passed per square metre in twenty-four hours.
A waterproof sock almost never fails from age. It fails from one of these, and three are avoidable.
Heat
A tumble dryer, an iron, or a radiator. Direct heat is the fastest way to finish one off and the most common. Air dry, always.
Fabric softener
Softener coats the holes the layer breathes through. The sock still keeps water out and stops letting sweat out, which is the worst of both.
Rubbing
The outer knit takes this, which is why there are three layers. But a sock worn in a boot with a rough interior, or over months on site, will eventually wear through.
A hole
A toenail, a thorn, or a sharp stone inside a boot. Once it’s pierced the waterproofing is gone and can’t be restored. No spray or reproofing treatment brings a waterproof layer back.
Questions
Common questions
Answered with the same facts as the rest of this page. If one of them contradicts something above, the answer above is the one that is wrong.
Something not here? Phone or email us
How do waterproof socks work?
A thin waterproof layer is sealed between two knitted layers. Its holes are too small for liquid water to pass through and big enough for water vapour to escape, so rain and puddle water stay out while sweat can move away from your foot.
What is a waterproof breathable membrane?
A thin sheet that blocks liquid water one way while letting water vapour through the other. It works because a water droplet is far bigger than a vapour molecule. HydroSox uses Porelle®, made by a separate company.
Why do waterproof socks need three layers?
Because the waterproof layer needs protecting on both sides. The inner knit keeps it off your skin and moves sweat towards it. The outer knit takes the rubbing inside a boot. A waterproof layer used as the wear surface wouldn’t last a season.
Can waterproof socks be reproofed?
No. Reproofing works on a water-repellent finish applied to a fabric surface. It can’t repair a waterproof layer. Once one is pierced or worn through, the waterproofing is gone for good.
What is hydrostatic head?
The standard measure of how much water pressure a fabric holds back before water passes through, given in millimetres. It’s the number worth asking any waterproof brand for. We don’t publish one yet because we don’t have independent test data.
Do all waterproof socks use the same membrane?
No, and many don’t say what they use at all. Some use a named third-party layer, some use an unnamed one, and some are just a tightly knitted or treated sock with no waterproof layer in it. If a listing doesn’t name one, that’s usually why.
Two decisions and a quantity. No account needed.