Why We Knit Our Underwear in Double Rib

Most underwear solves the problem of fit with chemistry. A percentage of elastane goes into the yarn, the fabric gives, and nobody asks any further questions. We took the other route and solved it with geometry — a slower fabric to knit and a harder one to get right, for reasons you can see by holding a pair up to the light.

The Garment That Works Hardest

Underwear is asked for more than anything else in a wardrobe and examined less. A pair of briefs is pulled over the heels, stretched across the hips, sat on for eight hours, carried through a few thousand steps and then washed at 30°C, and it is expected to come out of all of that in the shape it went in.

Which means that almost every real decision in a pair of briefs is a decision about elasticity: where the give comes from and how long it stays. There are two answers available. One is chemistry — elastane fibre gives because long polyurethane chains uncoil under load and recoil when released, with the fibre doing the work near the top of its range every single time. The other is geometry: building the give into the shape of the fabric itself, so that the yarn barely has to move.

We build ours on the second and use the first only where it earns its place. That's what defines our famous Briefs, Boxer Briefs and Tanktops

A Rib Is a Folded Fabric

In a plain jersey — the fabric of most T-shirts and most underwear — every loop faces the same way. In a rib they alternate: a column of face loops, then a column of reverse loops, then face again. One column of each gives the fine rib familiar from a classic cotton brief. Two and two gives Doppelripp, the double rib we knit.

The visible difference is texture. The one that matters is the cross-section. Each reverse column sits behind the plane of the face columns on either side, pulled back and hidden, so the fabric at rest is a row of closed pleats. It measures narrower than the yarn in it would suggest, because a good deal of its width is folded away out of sight.

That fold is the whole mechanism. Pull a rib across the ribs and you are not stretching anything — you are opening a bellows. The hidden columns swing forward into the plane, the pleats flatten out, and the fabric gains half its width again or more. Let go and they close.

The yarn barely participates. The loops rotate, trade length between their legs and their crowns and lean out of the fold, but the cotton is being bent rather than pulled. A fabric extending by 60% may be asking the yarn itself for a small fraction of that. Recovery is the same process in reverse: the folded state is the structure's resting state, the arrangement in which the loops sit most tightly packed and the yarn is least bent, so the bend straightens, the loops jam back against one another and the pleats shut.

Why That Matters Below the Waist

The force a rib exerts is gentle and the travel is long, which happens to be exactly what a brief needs. A seated body measures several centimetres more across the seat than a standing one, and over a day the fabric opens and closes dozens of times. A rib absorbs that by unfolding rather than by straining, so it comes back flat instead of keeping the shape of the chair.

The directionality matters as much. A rib gives around the body and hardly at all along it. On a boxer brief that is the difference between a leg that stays where it was set and one that works its way up the thigh over an afternoon — the fabric is free in the direction the body moves and firm in the direction it does not. It is the reason we can cut a longer leg without adding a silicone gripper to hold it down.

There is a comfort argument too, and it also falls out of the cross-section. Only the face columns touch the skin. The reverse columns sit behind them, so contact is intermittent and the troughs between the ribs form channels where air moves and moisture leaves. The same folds hold still air, which makes a double rib warmer in winter than its weight suggests and less clammy in summer than a flat jersey of the same cotton.

What We Specify, and Why

A rib only behaves like this if it is built properly, and most of what separates a good rib from a decorative one is invisible on the shelf.

Density decides most of it. A rib knitted with long loops has shallow pleats and very little to close; it looks like a rib and behaves like a jersey, pleasant in the hand and out of shape by the end of a season. We knit tight, which costs more yarn per metre and more time on the machine.

Yarn twist is close behind. A firmly twisted yarn is springier and resists being crushed flat, while a soft, low-twist yarn feels better on the first day and gives up sooner. We take the first.

Then there is relaxation, the step nobody sees. Rib has to be allowed to settle completely before it is cut. Pulled through dyeing and drying under tension, it leaves the mill already stretched, and it will shrink or twist the first time it is washed. Our fabric rests before it is cut, and it is measured at the width it takes when it is doing nothing — the relaxed width, not the stretched one. The fold is trusted to find the rest.

Elastane is still in there, at a few percent. It sharpens the speed of recovery, which on a long leg is worth having. What it does not do is carry the fit on its own.

Check It Yourself, in Thirty Seconds

None of this has to be taken on trust, which is the part we like about it. Stretch a rib across the ribs by about a third, hold for a moment and let go. A good one returns in a single movement. A poor one returns most of the way, hesitates and leaves a slightly wider band behind. You have just watched its whole future.

Then pull it the other way, along the ribs. It should barely give. A rib that stretches lengthwise has usually been stretched already, somewhere between the knitting machine and the cutting table.

Finally, hold it edge-on to the light and look for deep, closed folds with the reverse columns properly tucked away, not a shallow wave across the surface. Do it to ours, and do it to whatever is in the drawer at home.

It is a slower fabric to make and there is no way to put it on a label. But it is the only kind of elasticity that does not have an expiry date, because a fibre has to be asked to remember its shape — and a fold does not.