Yarn Defined

What Yarn Is

At its simplest, yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery and ropemaking. Thread is a type of yarn intended for sewing by hand or machine, and modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns designed specifically for hand or machine embroidery, often with a smoother surface and a stronger sheen than ordinary knitting yarn.

That short definition covers a wide range of products. A yarn may be made from a single fibre type or from a blend, it may be fine enough for lace or thick enough for a bulky sweater, and it may be sold as a small ball for handcrafts or as a large cone for a mill. What all yarns share is structure: fibres are held together, usually by twist, so that the strand acts as one continuous, workable length rather than as loose fibre that would pull apart.

Spun Yarn, Filament Yarn and Plies

Spun yarn is made by twisting or otherwise bonding staple fibres together to make a cohesive thread. Twisting fibres into yarn in the process called spinning can be dated back to the Upper Paleolithic, and yarn spinning was one of the very first processes to be industrialised. Spun yarns may contain a single type of fibre, or a blend of various types. Combining synthetic fibres, which can offer strength, lustre and flame-retardant qualities, with natural fibres, which offer water absorbency and comfort against the skin, is very common, and cotton-polyester and wool-acrylic are among the most widely used blends.

Yarns are made up of a number of plies, each ply being a single spun yarn. Singles are twisted together, or plied, in the opposite direction to make a thicker, more balanced yarn, and depending on the direction of that final twist the yarn is known as S-twist or Z-twist. Filament yarn works differently: it consists of very long continuous fibres, either twisted together or simply grouped together. Silk is a natural filament, synthetic filament yarns are used to produce silk-like effects, and texturised yarns are made by air texturising, which gives filament yarn some of the bulk and handle of a spun yarn.

Fibres, Blends and Yarn Weights

The fibre decides much of how a yarn behaves. Cotton gives a matte, breathable yarn, wool gives warmth, crimp and elasticity, and silk gives smoothness and shine. Alpaca, angora and cashmere appear in finer, more expensive yarns and blends, while polyester and other synthetics add strength, easy care and lower cost. Reading a yarn label therefore starts with fibre content: it predicts warmth, absorbency, drape, pilling tendency and how the finished cloth should be washed, long before colour or price enter the decision.

Thickness is described as yarn weight, which should not be confused with the physical weight of the ball or skein. Handcraft yarns are commonly grouped from finest to thickest as lace, fingering, sport, double-knit or DK, worsted, aran or heavy worsted, bulky and super-bulky, and the Craft Yarn Council of America has promoted a numbered system running from 1 for the finest to 6 for the heaviest. In commercial textiles, counts and deniers do the same job more precisely, expressing how much length is packed into a given weight.

How Yarn Is Measured and Bought

Yarn quantities are usually measured by weight in grams or ounces. In the United States, Canada and Europe, balls of yarn for handcrafts are sold by weight, with common skein sizes including 25 gram, 50 gram and 100 gram, or three-ounce, four-ounce, six-ounce and eight-ounce skeins. These measurements are taken at a standard temperature and humidity, because yarn can absorb moisture from the air. The actual length inside a ball varies with the heaviness of the fibre and the thickness of the strand, so a fine mohair skein can hold several hundred metres while a bulky wool skein of the same weight holds far less.

For a buyer, the practical lesson is to specify yarn completely: fibre and blend, spun or filament construction, ply and twist direction where it matters, count or weight category, colour and dye lot, and the put-up, meaning ball, skein, hank or cone. A complete description prevents the most common disappointments, such as a yarn that is the right colour but the wrong thickness, or a second order that knits up slightly differently because it came from another dye lot. Clear naming at the ordering stage is what turns a general idea of yarn into a repeatable material.

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