Dry heat and humid heat are different conditions, and they ask different things of a garment. In the desert, moisture leaves the skin almost as soon as it appears, and the task of a shirt is mostly to give shade. In the tropics the air is already carrying nearly all the water it can hold. Nothing evaporates quickly, and comfort depends on how a fabric behaves when it is damp. Linen in humid weather is a subject worth looking at closely, because it is where the fibre's nature is most plainly on show.

That nature begins in the plant. Linen is spun from the stem fibres of flax, and flax is a crop of damp places: the coastal belt of Western Europe, where certified Belgian linen has its origin, is a landscape of sea air, soft rain and mild summers. The fibre that results is strongly hygroscopic. It can take up moisture amounting to around a fifth of its own dry weight before it begins to feel wet to the hand, and it gives that moisture back to the air readily. A linen shirt on a humid day is doing quiet, continuous work between the skin and the atmosphere.

The second property is stiffness. Flax fibre is long and comparatively rigid, and cloth woven from it does not drape closely. It stands off the body in small folds, leaving a layer of air that moves each time the wearer does. In humid conditions this matters as much as absorbency. A fabric that rests against damp skin holds warmth there. A fabric that keeps its distance lets the slightest breeze pass underneath. The texture some people take for roughness in new linen is the same quality that keeps it comfortable in a monsoon.

It is as well to be honest about the limits. When the air is close to saturation, as it is on an August night in Singapore or on the Dubai Creek in September, nothing worn on the body stays entirely dry. Linen will feel damp at the collar and across the back at times, and it will crease more, not less, as it takes on moisture. That crease is a material fact, not a failure of care. What linen offers in these conditions is not dryness but ease: it does not cling, it dries quickly once the wearer steps into moving air, and it is fresh again after a night on a hanger.

Cut does a great deal of the work. A shirt with room through the body, a collar worn open and a sleeve that does not grip the arm will always be more comfortable in humidity than a close one, whatever the cloth. The Vibes linen shirt, with its oversized silhouette, shorter length and short sleeve, suits exactly these conditions. So does the Laos Short Sleeve Linen Shirt, which sits easily away from the waist. For her, the Amelia linen dress shirt works on the same principle: one garment, generous through the body, with air able to move from hem to collar.

Colour plays a smaller part, but a real one. Pale colourways take up less of the sun's warmth, and in damp heat every degree counts. White, Vanille and Oyster are the natural choices for the middle of the day. Deeper tones, Dubarry or Dark Blue, come into their own in the evening, when the sun is no longer a factor and a darker cloth is more forgiving at a table. Most PP linen shirts close with seashell buttons, which are indifferent to salt air and humidity; they were, after all, formed in the sea.

Care in a humid climate is simple and has one firm rule: never put linen away damp. Hang a shirt in moving air between wears, on a wide hanger, away from a closed wardrobe. In the tropics a washed shirt will dry on a line in the shade within a few hours, and line-drying leaves the fibre softer than any machine. Linen improves with this kind of use. Each wash relaxes the yarn a little further, and a shirt that has spent a season on the equator comes home more comfortable than it left.

It helps to see the fabric in the places it serves. In the Maldives, where the humidity rarely falls far and the breeze is constant, a short-sleeved linen shirt is close to the only thing a man needs between breakfast and dusk. On the north-east coast of Puerto Rico, where the rainforest of El Yunque meets the Atlantic at Río Grande, the afternoons bring warm showers that pass in twenty minutes, and a linen shirt caught in one is dry again before dinner. In the Gulf, the weeks at the end of summer are among the most humid of the year, and they are the weeks in which Dubai returns to its terraces.

For readers who would like the science at greater length, the journal's note on linen and breathability and the guide to Belgian linen go further. The short version is this. Flax grew up in wet air. It is not troubled by it. A shirt cut from it, with room for the air to move, will meet a humid day with composure, and ask very little in return.

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