Write the yarn spec

Two yarns of the same count and the same fibre can differ by a fifth in price, and the reason is always in these six lines. If you learn one thing here, learn the difference between the spinning systems, because it explains most of the gap between two quotations.

Count and ply

The thickness, and how many singles are twisted together. Ne is the usual cotton system and bigger means finer. Ply notation is the most expensive ambiguity in the trade: 2/40s normally means two 40s singles making a resultant 20s, but some mills use the same mark for the resultant, and the two readings differ twofold in fabric weight. Ask for singles and resultant stated separately, in writing.

Carded or combed

Combing pulls out the short fibres and neps before spinning. Roughly a sixth of the fibre leaves as noil and is sold on cheaply, so you pay for the fibre that left as well as the fibre that stayed. In exchange you get a cleaner, stronger, smoother yarn, and above about 40s it is not optional.

Ring spun

The oldest system and still the best. Strongest yarn, finest counts, the softest hand. It is the slowest and therefore the dearest, and it is what a good T shirt or a fine shirting is made from.

Compact or condensed ring

Ring spinning with the fibres drawn together before twisting. Fewer protruding fibre ends, so less hairiness, more strength and less pilling in the finished garment. A premium over plain ring, and worth it in fine counts and in anything that will be worn next to skin.

Open end, also called rotor

Much faster and much cheaper, and the yarn is bulkier, more even and roughly fifteen to twenty per cent weaker than a ring yarn of the same count. Practical up to about 30s. Denim, terry, home textiles and heavy jersey are largely rotor spun and none the worse for it, but a rotor yarn in a fine shirting is a substitution, not a saving.

Air jet and vortex

Very fast, very low hairiness, and stiffer in hand. Mostly used on polyester and blends. It is a different product rather than a cheaper version of ring yarn.

Twist, and the twist multiplier

How much the yarn is twisted for its thickness. More twist means more strength up to a point, then a harsher, livelier yarn. Weaving warp is twisted harder than weft, and knitting yarn is twisted softer than either, because a hard twisted knitting yarn makes a fabric that spirals. If a mill offers a weaving yarn for a knitting programme, this is why it will not do.

Twist direction, Z or S

Which way the twist runs. It matters when two yarns are plied and when a fabric relies on twist direction for its surface, such as a crepe. Wrong direction is not a quality fault, it is the wrong yarn.

Evenness and imperfections

Reported as U per cent or CV per cent for evenness, and as counts per kilometre of thin places, thick places and neps. These are what turn into visible streaks and specks in a plain dyed fabric, and they are the numbers a good mill will send you unasked.

Hairiness

Fibre ends standing off the yarn. High hairiness pills, low hairiness looks cleaner and dyes more evenly. It is one of the main things you are paying for in a compact yarn.

Strength, as RKM or CSP

Two ways of saying the same thing. It decides how the yarn behaves in weaving and knitting rather than how the garment wears, so it is mostly the mill next door’s problem, but a weak yarn slows their machine and they will price it.

Uster Statistics percentile

The trade’s shorthand for quality. A mill saying "25 per cent Uster level" means its yarn tests better than seventy five per cent of the world’s yarn on that property. It is a comparison against a published survey, not a pass mark, and it is worth asking which property they mean.

Waxing

A light wax on knitting yarn so it runs through the needles. Yarn for weaving is not waxed. It is a small thing that stops a delivery being usable if it is wrong.

What to put on the order for a cone of yarn

Every line below is one you can be given a straight answer on. A supplier who will not put one of them in writing is telling you something, and it is usually the most useful thing you will learn in the negotiation.

• Count, stated as singles and resultant separately, and the ply.
• Fibre and blend ratio, with the tolerance you will accept on the ratio.
• Carded or combed, and the spinning system: ring, compact, rotor, air jet.
• Twist multiplier and twist direction, and whether it is for weaving or knitting.
• The evenness, imperfection, hairiness and strength figures you require, with the Uster percentile if you work that way.
• Waxed or unwaxed, cone weight, cone type and the packing.
• Whether a test report per lot is required, and from whose laboratory.

Evenness, imperfections and hairiness are normally reported on Uster type testing equipment. The percentile refers to the published Uster Statistics survey. Ranges above are typical trade practice, not a specification.

These are standard trade definitions and typical published ranges, compiled by VeriMills for orientation. They are not a specification, they do not replace a test report, and where a figure here differs from your contract, your contract is the one that binds.