Raise your arm to hail a waiter. In some shirts the whole garment rises with it: the hem leaves the waistband, the collar tilts, the back pulls tight across the shoulder blades. In others the arm simply goes up and the shirt stays where it was. The difference is almost always the armhole. Of all the quiet marks of quality in a linen shirt, the armhole is the one most rarely discussed and most immediately felt.

What the armhole is

The armhole, called the armscye by tailors, is the opening in the body of the shirt into which the sleeve is set. Its height, its depth and its shape decide how the sleeve hangs and how the shirt behaves when the arm moves. It is drawn on the pattern and then sewn as a curved seam joining sleeve to body, usually meeting the yoke at the top. The guide to the linen shirt yoke explains how the yoke and the armhole work together across the shoulders.

The paradox of the high armhole

It seems logical that a larger, lower armhole would give more freedom. In practice it gives less. When the armhole is cut low, the sleeve joins the body far down the side, and raising the arm drags the body of the shirt upward with it. A higher, closer armhole lets the arm move inside a smaller circle, with the sleeve pivoting from near the shoulder joint. The body of the shirt stays still. This is why well-cut shirts often feel slightly closer under the arm and move more freely at the same time.

Why it matters more in linen

Linen has very little natural stretch, and PP's linen shirts are cut from linen alone. A cloth that does not give must be cut to move. In a stretch fabric, a poorly placed armhole is partly forgiven by the cloth; in linen it is not. The account of how linen stretches describes this in more depth. The consequence is that the armhole is one of the clearest signs of whether a linen shirt has been thought through.

The mirror test

A few simple movements tell most of the story. Stand in front of a mirror and raise both arms forward to shoulder height: the hem should rise only a little. Reach across the body as if for a seatbelt: the back should not pull tightly across the shoulder blades. Lift one arm overhead: the collar should stay close to the neck rather than lifting on the opposite side. Then look under the arm with the arms relaxed: a small amount of ease is normal, but folds of loose cloth hanging in the armpit suggest the armhole is cut too deep.

The relaxed exception

Not every shirt is meant to sit close. Relaxed and oversized silhouettes are cut with more volume throughout, and their armholes are often deeper as part of that intention. The Vibes linen shirt is cut in that relaxed way, and its looseness is the point. The question is not whether an armhole is high or low but whether it suits the intention of the shirt. The linen shirt fit guide discusses how different fits should sit on the body.

The seam itself

Look also at the seam. A clean, flat armhole seam lies smoothly against the body without a ridge; it has been set with care, with the ease of the sleeve distributed evenly so that there are no puckers at the top of the shoulder. The guide to linen shirt seams describes the main seam types and what they reveal.

Comfort in heat

There is one more reason the armhole matters in a warm-weather shirt. The underarm is where heat and moisture gather. A shirt that pulls tight there when the arm moves presses the cloth against the skin precisely where air most needs to circulate. A well-placed armhole leaves that space open, and the cloth can breathe where the body is warmest.

The men's shirts in the PP linen shirts collection are handmade at the atelier in Dubai and in Belgium. Try one on and raise an arm. The shirt will tell you more about its making than any label can.

Read more: What Makes a Shirt Truly Luxury  ·  Linen Shirt Cuffs