Why 97% Merino and 3% Lycra, and What We Gave Up

September 14, 2026 5 min read behind-the-brand

Composition tables are the most skipped section on any sock product page and the most predictive one. So here's ours, fully, with the part that works against us left in.

What's in most merino socks, and why

Pull up any well-regarded merino sock and you'll see roughly the same recipe.

Injinji Liner Crew Wool: 74% merino, 22% nylon, 4% Lycra, around $16 a pair. Smartwool: 66% merino, 33% nylon, 1% elastane.

Two different companies, two decades of iteration each, and they land within a few points of one another. When independent engineering converges like that, the convergence is usually telling you something.

What it's telling you is that a sock has two jobs that pull in opposite directions. It has to manage moisture next to your skin, which wool does well. And it has to survive being dragged across the inside of a shoe several thousand times a day, which wool does badly.

What nylon actually does

Wool fibre is fine, crimped and soft, and those are the properties that make it good against skin. They're also the properties that make it weak under abrasion. Wool wears through.

Nylon is the opposite. High tensile strength, high abrasion resistance, holds its shape. In a sock it functions as the structural component: it goes where the friction is and it takes the damage the wool can't.

That's why 20–30% is such a common figure. It's enough nylon to carry the mechanical load without enough to change how the sock feels or how it handles moisture.

So the honest version of the case against our specification is simple. Every brand with a long track record in this category puts nylon in their merino socks, and they are not doing it to save money. They're doing it because a sock without it wears through faster at the heel and toe.

I'd rather say that plainly than have you discover it in a review.

Why we went to 97% anyway

Two reasons, one good and one that I'd call defensible rather than obviously right.

The first is that the previous version failed on fibre. Our first production run was 24.6% merino against 33.1% acrylic, and it pilled within half a day of wear. I've written that up in full elsewhere. Acrylic had to go, and once you're removing the largest synthetic component you're rebuilding the specification rather than adjusting it.

The second is about what this sock is for. A hiking sock spends its life under load, on uneven ground, inside a boot, for hours of continuous friction. A dress sock spends its life in an office chair and on carpet, inside a smooth-lined leather shoe. Those are different mechanical environments, and the abrasion argument is much stronger in the first than the second.

That's a real distinction, and I want to be careful with it, because it's also exactly the kind of reasoning a person uses to justify a decision they already made. It is not the same as having tested it.

What we don't know yet

Here's the part that a product page wouldn't say.

I've had this specification for under two weeks. What I can tell you is what's in it and why. What I cannot tell you is how the heel and toe look after six months of real wear, because nobody has worn a pair for six months.

The abrasion question is genuinely open. It's the single biggest unknown about my own product, and the industry consensus points away from my choice.

What I can commit to is this: I'll publish the answer here when I have it, including if the answer is that the industry was right and we should add nylon back. That would be an expensive thing to find out and a cheap thing to write about, and the second doesn't excuse avoiding the first.

If you want a sock with a proven abrasion profile today, Injinji and Smartwool both publish their compositions and both have years of wear behind them. That's a genuine recommendation and I'd rather make it than have you buy on a claim I can't support yet.

How to read any sock's composition

This part is useful regardless of what you end up buying.

Look at the largest single component, not the wool percentage. A sock advertised as merino can be 24% wool and 33% acrylic. The headline fibre is chosen for marketing; the largest fibre determines behaviour.

Acrylic in quantity is a warning. It's cheap, it's warm, and pilling is its signature failure mode.

Polyester is not the same as nylon. Both are synthetics and they do different jobs. Nylon is the abrasion component. Polyester is usually there for cost and bulk, and it has a reputation for holding odour that wool doesn't share.

Elastane belongs in the cuff, not spread through the sock. Three per cent, knitted through the ribbed section, is doing one job. Look for brands that describe where it is rather than only how much.

A brand that doesn't publish full percentages has made a choice about that. Every claim on a product page is easier to make than the composition table, which is why the composition table is the one worth finding.

Common questions

Why do most merino socks contain nylon?

Wool fibre is soft and fine, which makes it comfortable and also makes it wear through under abrasion. Nylon carries the mechanical load at the heel and toe. Typical blends run 20–30% nylon for that reason.

Is 97% merino better than a 70/30 merino-nylon blend?

Not automatically, and it depends what you're optimising. More wool means more of the fibre that handles moisture as vapour. Less nylon means less abrasion resistance. A hiking sock and a dress sock face very different amounts of friction.

Will a sock without nylon wear out faster?

That's the open question. The industry consensus says nylon improves abrasion resistance, which is why it's near-universal in performance socks. We haven't had our current specification long enough to report on it, and we'll publish what we find.

What does the 3% Lycra do?

It's knitted through the ribbed cuff to hold the sock up, spread across the whole section rather than concentrated in one elastic band. A single band grips harder in one place and is what leaves a ring on your ankle.

Why did you change from the previous blend?

The first run was 24.6% merino against 33.1% acrylic and it pilled visibly after half a day. Acrylic pills; that's its characteristic failure. We stopped selling it and rebuilt the specification.