Two Numbers That Decide Everything

Before you wind a warp, two measurements quietly determine whether your cloth will be a softly draping scarf or a stout, hard-wearing upholstery sample. The first is the yarn count — how thick or fine your yarn actually is. The second is the sett — how closely you space those threads in the reed. Get the relationship between them right and the fabric behaves. Get it wrong and you will spend an afternoon wondering why a scarf feels like a doormat.

Neither number is difficult, but both are easy to misread, because yarn counts come in several different systems and sett depends as much on weave structure and finishing as on arithmetic.

Yarn Counts: What the Numbers Actually Mean

Yarn count, sometimes called grist, is simply a way of describing the mass of yarn per unit length. The trouble is that different fibres traditionally used different systems, and the numbers run in opposite directions depending on which one you meet.

• Metric count (Nm) — the number of metres in one gram. Higher numbers mean finer yarn. A 2/28 Nm yarn is two plies of a 28 Nm single, giving a resultant count of roughly 14 Nm.
• Cotton count (Ne) — the number of 840-yard hanks in one pound. Again, higher is finer. A 2/20 Ne yarn works out at about 10 Ne.
• Worsted count — based on 560-yard hanks per pound, still used for many British weaving wools.
• Tex and denier — the reverse logic. Tex is grams per 1,000 metres, denier is grams per 9,000 metres, so a larger number means a thicker yarn.

The practical point is that you cannot swap a 2/20 Ne cotton for a 2/20 Nm wool and expect the same cloth. Always convert to a common system, or better still, measure the yarn yourself.

Sett: Ends Per Inch and the Wraps-Per-Inch Shortcut

Sett is the number of warp ends per inch (EPI) that you thread through the reed. It governs how much of the cloth is yarn and how much is air. Too open and the fabric frays at the seams; too tight and the yarns abrade against each other in the heddles.

A quick way to estimate a sensible starting sett is the wraps-per-inch test. Wind your yarn around a ruler for one inch, keeping the wraps snug but not stretched, and count them. That figure, combined with your weave structure, gives you a working sett:

• Plain weave: roughly half the wraps per inch
• Twill: roughly two-thirds
• Satin and other long-float structures: roughly three-quarters

So a yarn wrapping at 24 wraps per inch might sit at 12 EPI in plain weave, 16 EPI in twill. These are starting points, not commandments — fibre, twist and finishing will all shift the answer.

Reeds, Dents and Practical Substitution

Reeds are sold in dents per inch, and you rarely own every size. That is fine, because you can vary ends per dent. A 10-dent reed threaded two ends per dent gives you 20 EPI; the same reed threaded three ends per dent gives 30 EPI. Sleying in a simple repeating pattern also lets you fine-tune a sett that sits between available reeds, though keep an eye on how the reed marks might show in a loose weave.

For balanced plain weave with the same yarn warp and weft, aim for slightly more picks per inch than ends per inch — often around five to ten per cent more, because the warp takes up during weaving. If your picks and ends match exactly, the cloth will usually finish slightly weft-faced.

Sampling: The Only Way to Be Sure

Every experienced weaver samples, not because the maths is unreliable but because it cannot account for everything. A sample of 15 to 20 cm is enough to answer most questions, and it costs a fraction of a ruined warp.

• Wind and thread a small warp at your proposed sett, ideally in two or three variations.
• Weave several inches at your intended picks per inch, and note the loom state.
• Cut the sample off, then finish it exactly as the final cloth will be finished — washed, fulled, pressed, steamed.
• Measure the finished sett and picks, and check the handle: does it drape, hold a crease, feel dense enough for its purpose?
• Record the numbers alongside the yarn details, so next time you are not guessing.

Fibre, Fulling and the British Difference

Wool is the great variable in British weaving. A Bluefaced Leicester singles will bloom and full in the wash, closing up a sett that looked generous on the loom. A tight, smooth Shetland worsted may barely move. Cellulose fibres such as linen and cotton behave differently again, and linen in particular gains sett as it swells in the loom.

This is why a sett that feels too open off the loom can be perfect after wet finishing. If you plan to full your cloth deliberately, sample a slightly wider sett than you think you need and let the finishing do the work.

Count and sett are not rules to obey but levers to pull. Learn your yarn, measure it honestly, sample without shortcuts, and you will find you can predict the cloth in your hands long before the last pick is beaten in.