Thread count, and why the number is unreliable
Thread count is the number of threads in a square inch of fabric, counting both directions — the warp running lengthways and the weft running across.
The problem is how the counting is done. A yarn can be spun from more than one strand, and a manufacturer who counts each strand rather than each yarn can double or treble the figure without changing the cloth at all. A genuine 300-count fabric woven from two-ply yarn becomes "600 thread count" on the packet. The textile standards for measuring this count yarns, not plies; the marketing does not have to.
The practical consequence is a ceiling. Single-ply cotton of the fineness used in bed linen runs out of room somewhere around 400 to 500 threads per square inch — beyond that there is physically no space to put more. So a figure of 800, 1,000 or 1,500 means one of two things: plies counted separately, or yarns spun so fine that the fabric is weaker and will wear through sooner. Neither is what the number is meant to imply.
Where thread count does mean something is at the bottom of the range. Below about 200 the fabric is likely to be thin and coarse. Between roughly 200 and 400, the differences owe far more to the fibre and the weave than to the count, and a well-made 200-count percale will outlast and outperform a 1,000-count anything.
Weave: percale and sateen
This matters more than the count and is almost never the thing on the front of the packaging.
Percale is a plain weave — one thread over, one thread under, in both directions. It is matte rather than shiny, feels crisp and cool, gets softer with washing without losing its structure, and is the more durable of the two. It is the hotel-sheet feel, and it suits anyone who sleeps warm.
Sateen is a satin weave, with more of the warp threads sitting on the surface before passing under. That exposed surface is what gives the lustre and the slippery, heavier hand. It feels warmer, drapes better and photographs beautifully. It also snags and pills more readily, because those long surface threads have nothing holding them down.
Neither is better. They are different fabrics for different sleepers, and someone who has decided they dislike cotton sheets has quite often simply been buying the wrong weave.
Cotton, and what "Egyptian" is worth
The thing that actually determines how cotton behaves is staple length — how long the individual fibres are. Long-staple cottons spin into smoother, stronger yarn with fewer loose ends, which means less pilling and a fabric that gets better rather than worse with age. Short-staple upland cotton, which is most of the world's crop, makes perfectly serviceable but rougher cloth that pills.
Long-staple varieties include Egyptian Giza cotton and the American Pima, sold under the Supima trademark when it is certified. Combed cotton has had the short fibres removed, which is a genuine improvement for the same reason.
The difficulty is that "Egyptian cotton" is a description, not a guarantee. The term is used loosely enough, and has been found wrong often enough in testing, that on its own it means very little. Supima is at least a controlled trademark. For Egyptian cotton the useful signals are a named variety such as Giza, a certification mark, and a seller willing to say which.
Linen
Linen is spun from flax, and it behaves unlike cotton in ways that suit some people completely and irritate others.
It is the strongest of the common bedding fibres and unusually is stronger wet than dry, which is why linen sheets survive decades of washing and tend to be the ones that get inherited. It carries moisture away quickly and holds a loose structure that moves air, so it feels cool in summer without feeling thin in winter. It softens substantially over the first year and keeps going.
It also creases, permanently and immediately, and no amount of ironing changes that for long. Anyone who minds that will not be converted. It is sold by weight in grams per square metre rather than by thread count, since the thread count of a linen weave is necessarily low and says nothing useful.
Silk, measured differently
Silk bedding is not rated by thread count either. The measure is momme, a weight-based figure, and bedding silk generally sits between about 19 and 22 momme — lighter than that and it is too fragile to launder repeatedly, heavier and the cost climbs without much gain.
"Mulberry silk" simply means silk from Bombyx mori silkworms fed on mulberry leaves, which is the standard cultivated silk rather than anything exotic. The practical appeal of silk is a very smooth surface that does not pull at hair or crease skin, and good moisture handling. The practical drawbacks are the cost, the laundering, and a surface that snags on a rough fingernail.
Lyocell, which is the "eucalyptus silk"
This is the fibre behind most of the bedding sold as eucalyptus silk, and it contains no silk whatever.
Lyocell is a regenerated cellulose fibre: wood pulp dissolved in a solvent and spun into filament. TENCEL is the best-known brand of it, and the pulp used is commonly eucalyptus. What distinguishes lyocell from older regenerated fibres is the process — the solvent is recovered and reused in a closed loop, which is why its environmental profile is better than viscose made the conventional way.
As a fabric it is smooth, drapes heavily, handles moisture very well and resists creasing. It is a reasonable thing to buy. "Eucalyptus silk" is simply a nicer-sounding name for it, and the giveaway is that lyocell is itself a permitted fibre name, so a composition label on genuine material will say lyocell. If the front of the packet says silk and the label says lyocell, the label is the accurate one.
Bamboo, which the label has to call viscose
Bamboo bedding is the clearest case of a marketing name diverging from a fibre name.
Bamboo can be processed mechanically into a genuine bamboo fibre, but almost nothing sold as bamboo bedding is made that way. The normal route is chemical: bamboo cellulose dissolved and regenerated, which produces viscose. Under the textile labelling rules that apply here, derived from EU Regulation 1007/2011, fibre names come from a permitted list — viscose, modal, lyocell, cupro and so on — and bamboo is not on it. The composition label must therefore say viscose. A phrase such as "viscose made from bamboo" is allowed alongside; "100% bamboo" on a chemically processed fabric is not accurate, and regulators across Europe and in the United States have acted against it.
Two things follow. The fibre is viscose, so it should be compared against other viscose rather than against cotton or linen. And the antimicrobial property often claimed for bamboo belongs to the plant: testing institutes are clear that regenerated fibre made from bamboo does not generally retain it.
None of which makes it bad bedding. Viscose is soft, cool to the touch and drapes well. It is weaker when wet than cotton and tends to need gentler laundering.
Wool
Mostly encountered as duvet and mattress-topper filling rather than as sheeting. Wool handles moisture unusually well, absorbing a good deal before feeling damp, which is what gives it a reputation for evening out a sleeper who overheats and then chills. It is heavier than down for the same warmth, does not compress as much, and is naturally flame-resistant. It usually needs specialist cleaning.
Duvets: what tog actually measures
Tog is thermal resistance and nothing else. It is measured on a togmeter to a British Standard, on a new duvet laid flat, with a permitted margin of half a tog either side of the stated figure.
Three things follow that buyers routinely get wrong:
- Tog says nothing about quality. A cheap duvet and a good one can share a rating. What differs is how long they hold it — ratings fall as filling compacts and with every wash, and poor filling falls fastest.
- Tog is not weight. A light down duvet and a heavy synthetic one can be equally warm. Down achieves a given tog at lower weight, which is most of what people are paying for.
- The laboratory figure is approximate in use, because it is measured flat and a real sleeper drapes it.
The British Standard range runs from about 4.5 for summer to 15 for a cold winter. 13.5 has long been the standard British winter duvet, though 10.5 and 12 have gained ground as central heating has become more consistent. An all-season pair — a 4.5 and a 9 or 10.5 that button together — covers the year more comfortably than one heavy duvet.
On filling, down and feather is lighter and warmer per gram, lasts longer and costs more; look for a stated down-to-feather ratio rather than the word "down" alone, and for traceable sourcing. Synthetic is washable, suits anyone with an allergy to dust rather than to feathers, and is the sensible choice for a child's bed, which will at some point need to go through a machine at short notice.
Where adult bedding is genuinely wrong for a child
This is the one part of the subject that is a safety matter rather than a preference, and the numbers make it plain.
A standard British adult winter duvet is 13.5 tog. A quilt for a child over one year should be no more than 4 tog. A baby's sleeping bag goes down to 0.5 tog for summer, and a first-size bag should not exceed 4 tog, with around 2.2 being typical. An adult duvet on a small child is not a generous gesture; it is three times the thermal resistance the guidance allows.
Alongside that, for any baby under one year: no duvet, no cot quilt, no pillow, no cot bumpers and nothing weighted, all of which are associated with an increased risk of sudden infant death or with the covering reaching the head. Blankets, if used, are thin, single-layer and tucked no higher than the shoulders. The room sits at 16 to 20°C.
Mattresses have their own standards — BS 7177, or BS EN 16890 for cot, crib and travel-cot mattresses — and need to be firm, entirely flat, and fitted to the cot with no gaps, with a waterproof cover. The safer sleep detail is under safer sleep for babies, and weighted bedding specifically under weighted blankets.
One correction worth making
Advice written for an American readership often tells parents to look for flame-retardant sheets and blankets. That instruction does not translate. The flammability rules here apply to upholstered furniture, mattresses and children's nightwear — bed linen is outside their scope, and flame-retardant sheets are not a category a British shopper will find. Looking for the label will simply waste time.
What actually makes bedding last
- Two sets in rotation rather than one in constant use, which roughly doubles the life of both.
- Cooler washes and a lower spin. Most wear happens in the machine rather than in the bed.
- No fabric softener on cotton or linen — it coats the fibres, reduces absorbency and makes towels and sheets feel worse over time, not better.
- Line drying or a low tumble. Heat is what breaks down elastic in fitted sheets and shortens the life of a duvet's filling.
- Duvets and pillows aired and washed as the label allows, and replaced when they stop recovering their loft.
And the general rule for the category: buy the weave and the fibre, check the composition label rather than the front of the packet, and treat any four-figure thread count as a reason to look more closely rather than a reason to pay more.