7 minute read
Every October I change my bed setup. The stonewashed cotton I sleep under from spring goes into the cupboard, and the brushed cotton comes out.
Stonewashed cotton feels cold when I first get in, and it cools down fast. Brushed cotton doesn't get that cold at first. It feels as if the bed is already warm.
People who buy our duvets often ask me which cover I recommend, and where to find it. My answer is always that it depends, and then I ask questions back. Do you sleep warm or cold? How warm is your bedroom? Do you wake up damp, or do you take a long time to warm up? The cover is the layer your skin touches all night, and it decides whether the warmth and moisture the duvet handles can get through at all, so the right one depends on how you sleep.
This post is the long version of that conversation: what a good cover does, how the fabrics in the shops differ, and where I would look for one to go with an alpaca duvet.
"Brushed cotton doesn't get that cold at first. It feels as if the bed is already warm."
Agnieszka Sela, founder of UNWONTED
What a good cover does
A good cover is one you do not notice. You get into bed and it feels right for the season, you sleep through the night without waking up damp, and after a hundred washes it is still soft and whole. In practice that comes down to six qualities.
It lets moisture through. During the night the body releases moisture as water vapour. Fabrics differ a great deal in how much of it they take up: polyester absorbs about 0.4% of its own weight, cotton about 8.5% and viscose about 13% under standard conditions. A cover that takes up and passes on moisture keeps the air next to your skin dry. A cover that does not holds the damp between you and the duvet, however good the filling inside is. An alpaca duvet takes up water vapour and releases it gradually into the room, but only if the moisture can reach it through the cover.
It feels right at the first touch. Some fabrics feel cool when you get into bed and others feel warm from the first moment. Textile researchers measure this as the warm or cool feeling of a fabric, the speed at which it draws heat from your skin in the first moments of contact. Smooth, flat-woven fabrics touch the skin at many points and draw heat away quickly, so they feel cool. Brushing lifts the fibres into a soft nap, the fabric touches the skin at fewer points and holds a layer of air, so it draws heat away more slowly. A study of napped fabrics found significantly less heat flow through the napped side than through the smooth side at first contact, and earlier work found that the hairier a fabric, the less cool it feels. In summer you want the cool feeling, in a cold bedroom the warm one.
It is woven closely enough. The cover protects the duvet from dust, skin and everyday dirt. A closely woven fabric does this better, but a very dense one lets less air through, so a good cover finds the balance for its season.
It can be washed hot. An alpaca duvet should only be aired and spot cleaned, so the cover takes over the hygiene. Cotton and linen can usually be washed at 60°C, the temperature hospital guidance recommends for bedding when someone is allergic to house dust mites.
It is made without harmful substances. An OEKO-TEX STANDARD 100 label means the fabric has been tested for substances harmful to health. GOTS goes further and certifies that the cotton is organic and processed under set environmental and social rules.
It fits exactly. A cover that is too small squeezes the filling, and one that is too large lets the duvet shift and bunch inside. Buy it in exactly the size of your duvet.
The fabrics you will find in shops
Cotton is by far the most common material, with around 63% of the bed linen market. Other common materials are polyester and cotton-polyester blends, linen, silk, and fibres made from wood pulp, such as lyocell and viscose, which is often sold as bamboo.
Labels mix up three different things. The fibre is what the threads are made of, such as cotton or linen. The weave or knit is how the threads are put together, such as percale, sateen or jersey. The finish is what is done to the fabric afterwards, such as stonewashing or brushing. The same cotton can feel crisp, silky, soft or warm depending on the weave and the finish, so it helps to know which of the three a name refers to.
Linen
What it is: a fibre from the stem of the flax plant, usually woven in a plain weave, one thread over and one under. Linen is often sold washed or stonewashed, a finish that makes it softer from the start.
What it does: the fibres are long and smooth, the fabric lets air through easily and it insulates less than cotton, so it feels cool and dries quickly. A 2024 review of sleep studies in the Journal of Sleep Research found that linen sheets improved sleep quality in warm conditions, compared with sheets made of a cotton and polyester blend. Unwashed linen feels firm at first and softens with every wash.
Most suitable for summer and for people who sleep warm all year.
Cotton
Cotton is soft, takes up moisture and washes well. What separates one cotton cover from another is the weave and the finish.
Percale is a weave. The threads cross one over and one under, tightly, which gives a smooth, crisp, matte fabric with a cool first touch. New percale is crisp and softens over many washes. Most suitable from spring to autumn, and in summer for people who do not like linen.
Sateen is a weave. Each thread runs over several threads before it goes under one, so more of the thread lies on the surface. The fabric is smooth, slightly shiny and drapes heavily, and it is usually denser than percale, so it holds a little more warmth. Most suitable for autumn and winter.
Stonewashed cotton is a finish. The fabric, usually a plain weave and sometimes a percale, is washed with pumice stones or enzymes after weaving or sewing. This breaks in the fibres, so the fabric is soft and relaxed from the first night instead of crisp, and it has a lived-in, creased look that does not need ironing. Most suitable for spring and autumn.
Seersucker and crepe are crinkled cottons. Seersucker gets its puckered stripes in the weaving, when some threads are held at a different tension from others. Crepe gets its crinkled surface from tightly twisted threads or from a finish. Either way the fabric touches the skin at fewer points, feels airy and needs no ironing. Most suitable for summer.
Brushed cotton, often sold as flannel, is a finish. After weaving, the surface is brushed so that fine fibres rise into a soft nap. The nap holds a thin layer of air and touches the skin at fewer points, which is why the fabric feels warm from the first moment. It is what I sleep under in winter. Most suitable for winter and cold bedrooms.
Jersey is a knit, not a weave. The thread is looped like a T-shirt instead of crossed, so the fabric stretches, feels soft and clings a little to the body, which makes it feel warm. Most suitable for autumn and winter, for people who like a close, soft feel.
Silk
What it is: a natural protein fibre spun by silkworms, usually woven as a satin for bedding, which gives the familiar shine.
What it does: very smooth and light, and it takes up a fair amount of moisture. It is expensive and delicate, and most silk bed linen has to be washed cool, by hand or on a gentle cycle, so it cannot carry the hygiene of the bed the way cotton and linen can.
Most suitable as a pillowcase for people who want a smooth surface for skin and hair, more than as a duvet cover.
Lyocell and bamboo viscose
What it is: fibres made by dissolving wood or bamboo pulp and spinning it into new threads. Lyocell, also sold under the brand name Tencel, and viscose are made in different processes. A cover sold as bamboo is almost always viscose made from bamboo pulp, not a natural bamboo fibre.
What it does: smooth, slightly shiny and cool to the touch, and it takes up more moisture than cotton. It usually needs a cooler wash than cotton.
Most suitable for summer and for people who sweat at night.
Polyester, microfibre and cotton-polyester blends
What it is: polyester is a synthetic fibre made from oil. Microfibre is polyester spun into very fine threads and often brushed to feel soft. Blends combine cotton and polyester, often half and half.
What it does: cheap, light and quick to dry, and it rarely creases. Polyester absorbs almost no moisture, so the damp your body releases stays between you and the duvet and the bed can feel clammy. Blends behave somewhere between cotton and polyester.
Most suitable for guest rooms and short stays. With a natural duvet, it works against the filling.
Our perfect match - TAMEKO
TAMEKO is a Copenhagen textile studio, and in 2026 we set up a bed together at the Summer Nights installation during 3daysofdesign. Its bed linen is designed by Space Copenhagen and meets the qualities above: it is made only of natural fibres, linen and cotton, it is OEKO-TEX certified, it can be washed at 60°C, and it comes in white, natural and grey tones that sit well next to the natural colour of alpaca fleece. It comes in two fabrics.
Merrow linen duvet cover: 100% European flax linen in a plain weave, 160 g per square metre, in white, natural and light grey.
Cove cotton duvet cover: stonewashed cotton, 110 g per square metre, soft from the first night, in white, natural and warm grey.
How to choose a TAMEKO cover for your UNWONTED duvet
1. Choose the fabric by season and by how you sleep.
| Season | UNWONTED duvet | TAMEKO |
|---|---|---|
| Summer | All-season, 400 g/m², or the cover alone on the hottest nights | Merrow linen |
| Spring and autumn | All-season, 400 g/m² | Cove stonewashed cotton |
| Winter | Winter, 600 g/m², in bedrooms below about 16°C | Cove, with a throw over the duvet on the coldest nights |
If you sleep warm, Merrow works all year, also with the winter duvet. If you feel the cold, choose Cove. TAMEKO does not make brushed cotton, so on the coldest nights add one of its throws over the duvet: Tate in cotton, Dale in linen, or the Ren alpaca blanket. A layer on top adds warmth without blocking the moisture that leaves your body during the night.
A hot water bottle is another simple way to take the chill off a cool cover in winter. Place it under the duvet a few minutes before you go to bed, and the cover will already feel warm when you get in, much as brushed cotton does. Fill the bottle no more than two thirds with water that has boiled and cooled for a few minutes, and take it out when you get into bed.
2. Choose the cover in exactly the size of your duvet.
| UNWONTED duvet | TAMEKO Merrow linen cover | TAMEKO Cove cotton cover |
|---|---|---|
| 140×200 cm | 140×200 cm | 140×200 cm |
| 200×200 cm | 200×200 cm | 200×200 cm |
| 200×220 cm | 200×220 cm | 200×220 cm |
| 240×220 cm | 240×220 cm |
3. Finish the bed. Cove also comes as fitted sheets for mattresses from 90 to 180 cm wide, and both Merrow and Cove come as pillowcases in the common European sizes. Choose and mix the colours as you like.
UNWONTED alpaca duvet
100% Polish alpaca fleece in a GOTS organic cotton shell. All-season 400 g/m² or winter 600 g/m².
Caring for the cover and the duvet
Wash the cover as often as you like, following its care label. Air the duvet regularly, outdoors when you can, and spot clean it when needed. Never wash an alpaca duvet in hot water or tumble dry it, because the fibre felts. With a cover on at all times, the duvet itself needs very little. For choosing between our two warmths, read all-season or winter duvet, and for sizes, our duvet size guide.