What Is Wool Fabric?
Wool fabric is any woven or knitted cloth made from the fleece of sheep, either alone or blended with other fibres. In labelling, the word wool refers specifically to sheep fibre. Other animal fibres such as cashmere, mohair and alpaca are hair fibres with their own names, though they are processed on similar machinery and are often blended with wool. Because the fibre is so adaptable, wool fabric ranges from fine, light jersey to dense, heavy overcoating.
What the fibre does is unusual. It insulates when it is cold, it breathes when it is warm, it stretches and recovers, and it handles moisture well. Those traits make wool the benchmark for warm outer layers, tailoring and knitwear, and it explains why people compare other fibres against it. Our overview of clothing fabrics places wool among the alternatives.
The next sections cover the fibre itself, the two yarn systems, the main types of wool, how it is woven and knitted, and the practical issues of itch, felting and care.
Wool Fibre Basics: Crimp, Scales and Moisture
Under a microscope, a wool fibre is crimped, which means it is naturally wavy. The crimp creates tiny air pockets in yarn and fabric, which is where much of wool's insulation comes from, and it gives the fibre elasticity: stretch it and it springs back. The outer surface of each fibre is covered with overlapping scales, a little like roof tiles, and these scales are the reason wool can felt, which we cover below.
Wool also takes up moisture vapour into the fibre and releases it slowly, so a wool garment can feel dry to the touch even when it has absorbed a significant amount of water vapour. The approximate standard moisture regain of wool, about 16 per cent of dry fibre weight, is higher than that of cotton or polyester. That is a published reference value, and real behaviour depends on the fabric. The practical outcome is a fibre that tolerates temperature swings well and tends to resist odour.
Fibre diameter, measured in microns (millionths of a metre), is the other key variable. Finer fibres feel softer against the skin, and coarser ones feel more rugged and can prickle. The measure explains most of the difference between a fine merino jersey and a tweed.
Woollen vs Worsted: Two Yarn Systems, Two Looks
The same wool can be spun in two ways, and the yarn system shapes the fabric more than most buyers expect. Woollen yarns are made from carded fibres of mixed length, which are fluffy and lofty with a fuzzy surface. Worsted yarns are made from combed, longer fibres laid parallel, which are smooth, fine and strong. The table summarises the difference.
Woollen vs worsted yarns and fabrics
| Feature | Woollen | Worsted |
|---|---|---|
| Fibre preparation | Carded; shorter and longer fibres mixed | Combed; shorter fibres removed, long fibres aligned |
| Yarn | Fuzzy, lofty, uneven, trapped air | Smooth, fine, even and strong |
| Fabric surface | Soft, matt and textured; often milled or brushed | Crisp, clean and smooth with clear weave definition |
| Warmth and feel | Warm and bulky | Cooler and lighter for the same warmth, with a sharper drape |
| Typical fabrics | Tweed, melton, flannel, Shetland-style knits | Suiting, gabardine, fine knitwear |
| Pilling tendency | Surface fuzz can pill with wear | Lower, thanks to long fibres and a smooth yarn |
General descriptions of the two systems. Many fabrics sit between them, and finishing changes the result.
When a supplier quotes wool fabric, ask which system is used. A woollen flannel and a worsted gabardine behave nothing alike, even in the same weight.
Types of Wool: Merino, Lambswool, Shetland and Others
Wool types are named by breed, by the age of the sheep, or by the processing. The names carry real meaning, but they are also used loosely in marketing, so ask for the fibre diameter and composition rather than relying on a name alone. Our dedicated guide to merino wool covers the finest of these in more depth.
Common wool types
| Type | What it is | Typical character | Typical uses |
|---|---|---|---|
| Merino | Wool from the Merino sheep breed | Fine, soft and elastic; the common choice for next-to-skin knits | Base layers, jersey, fine knitwear, suiting |
| Lambswool | Wool from a first shearing of a young sheep | Soft, light and springy | Sweaters, scarves, soft knits |
| Shetland wool | Wool from the Shetland sheep breed | Traditionally springy with a slightly rustic hand | Sweaters, scarves, tweed-style woven cloth |
| Crossbred and coarser wools | Wool from sturdier breeds | Stronger, more textured, sometimes prickly | Coating, tweed, rugs, outerwear |
| Recycled wool | Fibre recovered from existing wool garments or offcuts | Often shorter fibres, blended with virgin wool or other fibres | Blankets, coating, knitted items |
General descriptions. Names and qualities vary by supplier and region.
Cashmere, mohair and alpaca are separate fibres, not types of wool in the strict labelling sense. They are sometimes blended with wool to add softness, lustre or warmth.
Woven Wool Fabric: Suiting, Flannel, Melton and Tweed
Woven wool fabric covers several well-known cloths, each defined by its yarn system, weave and finishing. Worsted wool in plain weave or twill makes suiting and gabardine, a fine, tight cloth with sharp definition. Woollen cloths are usually napped or milled. Wool flannel is brushed to raise a soft surface, and our flannel fabric guide compares wool flannel with the cotton versions.
Melton is a dense woollen cloth that has been milled and cropped so the weave is hidden, making a smooth, felted surface that resists wind and fraying. It is a classic overcoating. Wool coating more generally covers heavy fabrics for coats and jackets. Tweed is a rough, textured woollen cloth, traditionally associated with outdoor use, and often yarn-dyed in flecked colours. Each of these fabrics is built to a specification by a mill that specialises in it.
Because wool wovens can be fussy to cut, press and line, tailored production usually relies on factories that specialise in tailoring. That is a different skill set from casual jersey and denim.
Wool in Knitted Forms: Jersey, Sweaters and Wool Blends
Wool is also very widely knitted. Fine wool jersey, usually merino, is used for t-shirts, base layers and dresses. Heavier gauges make sweaters, cardigans, hats and scarves. Knitwear can be made in two ways. Fully fashioned or flat-knit garments are knitted to shape on flat machines, and cut-and-sew knitwear is made from circular-knitted fabric that is cut and sewn like jersey. They are different businesses, and our knitwear manufacturer guide explains the distinction.
Boucle and other textured yarns can also be made with wool, in knitted and woven forms, and our boucle fabric guide shows how those textures behave in production.
Typical weights of wool fabrics
Typical grams per square metre
Typical ranges only; they vary by product, mill and construction. Woven bars are in indigo, knit bars in the second colour.
Use the ranges to calibrate a brief. A fabric labelled wool can be a light jersey or a very heavy overcoat, so the weight must always be specified.
Wool Blends: Why Wool Is Mixed with Other Fibres
Few wool garments are pure wool. Blending is used to change cost, durability, handle and care. The table sets out the main blends and the reasons for them. A blend must be labelled with the percentages of each fibre, so that content must be accurate; see the labelling note near the end of this guide.
Common wool blends and why they exist
| Blend | What it adds | Typical use | Trade-offs |
|---|---|---|---|
| Wool and polyester | Better crease recovery, strength and easier care; often lower cost | Suiting, trousers, uniforms | Less breathable than pure wool; can pill |
| Wool and nylon | Strength and abrasion resistance | Socks, hard-wearing knitwear, coating | Reduces the natural fibre share |
| Wool and viscose | Softer drape and a smoother surface | Lightweight knits, shirts | Viscose is weaker when wet |
| Wool and elastane | Comfort stretch and recovery | Fitted knits, trousers | Heat and care limits from the elastane |
| Wool and cotton | A cooler, drier handle and lower cost | Casual knits, jersey | Less warmth and springiness than pure wool |
General trade-offs. Exact behaviour depends on ratio, yarn and construction.
Blends can also make a wool-look fabric more affordable and more durable, though they change the sustainability and recycling picture. See the sustainability section for how to treat such claims.
Indicative Ratings: Wool Against Other Fibres
The chart gives an indicative picture of how wool compares with cotton, polyester and acrylic on the properties buyers ask about. Fine wool and coarse wool differ, so the wool column describes a typical fine-to-medium wool fabric.
Wool fabric compared with other fibres (indicative)
1 dot = low, 5 dots = high
| Wool | Cotton | Polyester | Acrylic | |
|---|---|---|---|---|
| Warmth for weight | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Breathability | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Odour resistance | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Durability and abrasion | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Ease of care | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
| Softness against the skin (fine grade) | ●●●●● | ●●●●● | ●●●●● | ●●●●● |
Indicative ratings based on typical fabric/process characteristics, not laboratory results.
Wool leads on warmth and odour resistance and loses on ease of care, which is why so many buyers choose a blend. Our acrylic fabric guide explains the synthetic alternative to wool in more detail.
Why Wool Can Itch, and What Controls It
Itch is the most common complaint about wool, and it has a physical cause. The ends of coarse fibres press against the skin and trigger a prickling sensation, so the fibre diameter and the proportion of coarse fibres in the yarn decide the feel. Finer grades such as merino and lambswool usually feel soft, while coarse grades can be uncomfortable against bare skin. Surface treatments, brushing and blending with softer fibres can reduce the effect, but they do not change the fibre.
For a garment worn next to the skin, ask for fibre diameter information and a wear test on a bare forearm, and consider a lining or a blend. For outerwear, a coarser wool is often acceptable because it is worn over a layer.
Felting, Shrinkage, Moths and Care
Wool care follows from its structure. Under heat, moisture and agitation, the scales on neighbouring fibres lock together, and the fabric tightens, thickens and shrinks permanently. This is felting. It is used deliberately to make milled cloth such as melton, but in a finished garment it is a risk. Washable wool is treated to reduce felting, and standard care labels for wool recommend a wool cycle, cool water, gentle handling, flat drying and minimal heat.
Moths are the other well-known risk. The larvae feed on keratin, the protein in wool, so garments stored dirty are more vulnerable than clean ones. Cleaning before storage, airtight or ventilated storage and checking regularly are the usual advice. Dry cleaning is common for tailored wool, and the care label should reflect the construction as well as the fibre. For test names and requirements such as shrinkage and colour fastness, see our garment testing guide.
Wool care points for a care label and customer advice
- Wash cycle and temperature suited to wool, or dry clean only if the construction needs it
- Flat drying, and no tumble drying unless the fabric is treated for it
- Low iron temperature with a cloth between the iron and the fabric if needed
- Clean the garment before long storage and use ventilated, moth-aware storage
- Shrinkage requirement confirmed by a wash test of the actual fabric
Care wording must be confirmed against the actual fabric and finishing.
Sustainability and Standards for Wool
Wool is a natural, renewable and biodegradable fibre, and a well-made wool garment can last for many years. That is a real advantage, but the picture has other parts. Sheep are livestock, and the footprint of wool depends on the farm: land use, grazing management and livestock emissions. Processing also matters, because scouring, dyeing and finishing use water, energy and chemicals. Animal welfare practices vary between farms and regions, and these concerns are why standards exist.
The Responsible Wool Standard (RWS) is a voluntary standard that addresses animal welfare and land management on farms, with chain-of-custody checks to follow the wool through production. If a supplier claims RWS, ask for the certificate and for the transaction documentation that links it to your order. Broader chemical and mill certifications, such as OEKO-TEX Standard 100, are also worth asking about. Our guide to sustainable fabrics explains how to read environmental claims with appropriate caution.
Natural does not automatically mean low impact. Ask which farms, which processing, which standard and which certificate covers your fabric, and keep the paperwork.
How to Specify Wool Fabric for a Mill or Factory
A wool fabric specification should be tighter than one for cotton, because the variables are so many. State the fibre composition with percentages, the yarn system (woollen or worsted), the fibre diameter or a handle description, the construction and weave, the finished weight in GSM, the width, the finish, the shrinkage and colour fastness requirements, and any certification you need. Add the intended garment so the mill can match construction to use.
Five steps to specify wool fabric
- 1Define the garmentSay whether it is outerwear, a knit, a shirt or a base layer, and how it is worn.
- 2Choose the fibre and blendDecide on pure wool or a blend, and the percentages.
- 3Set weight and handleGive GSM, yarn system and fibre diameter or a physical reference.
- 4Add performance and careSpecify shrinkage, pilling, colour fastness and care wording.
- 5Request swatches and a wash testJudge the actual cloth, wash it, and compare it to the specification.
In the UK, garments are normally required to carry accurate fibre content labels, and terms such as wool have specific meanings. The rules change, so confirm the current requirements with your factory or a test house. Our UK clothing labelling guide covers the basics.
Where Wool Sits at Ruhrose
Wool fabric is outside Ruhrose's core. We develop hoodies, jersey, denim and woven casualwear in Bangladesh for UK buyers, and our expertise is in cotton and cotton-blend knits and woven fabrics. If you need wool suiting, coating, fine merino knits or fully fashioned knitwear, the right route is a specialist wool mill or a knitwear manufacturer, and our knitwear manufacturer guide is a good place to start. Wool or wool-blend elements can feature in casual pieces, for example a wool-blend trim or panel, but only case by case, and always sampled before bulk. We would rather tell you early what we do not do than promise it.