Yarn thickness is stated as a count: tex is the weight in grams of 1,000 metres, so a lower number is finer, while Ne is the number of 840-yard hanks in a pound, so a higher number is finer. The two convert as tex = 590.5 ÷ Ne, so Ne 20 is 29.5 tex, and a 100 m skein of it weighs 2.95 g.
Part of Spinning Frame
Measuring yarn thickness by weight per length, and converting between the English cotton count, the metric count and tex.
Count Is A Weight Per Length
A yarn’s thickness is stated by how much it weighs for a given length, because diameter is hard to measure on a soft, fuzzy strand. There are two kinds of system. In a direct system the number is the weight of a fixed length, so a bigger number is a thicker yarn. In an indirect system the number is the length of a fixed weight, so a bigger number is a finer yarn.
The overview names three:
- Tex (direct): the weight in grams of 1,000 metres. Lower is finer.
- Ne, the English cotton count (indirect): the number of 840-yard hanks per pound. Higher is finer; Ne 20 is medium.
- Nm, the metric count (indirect): the number of kilometres per kilogram, which is the metres per gram. Higher is finer.
The Conversions, Worked From Definitions
One yard is 0.9144 m and one pound is 453.59 g (standard unit definitions). A yarn of Ne 1 is one 840-yard hank per pound: 840 × 0.9144 = 768.1 m weighing 453.59 g. Per 1,000 m that is 453.59 ÷ 768.1 × 1,000 = 590.5 g, so Ne 1 is 590.5 tex and
tex = 590.5 ÷ Ne, Nm = 1,000 ÷ tex, so Nm = 1.693 × Ne.
The overview’s remark that 30 tex is approximately Ne 20 checks: 590.5 ÷ 20 = 29.5.
| Ne | Tex | Nm |
|---|---|---|
| 10 | 59.1 | 16.9 |
| 16 | 36.9 | 27.1 |
| 20 | 29.5 | 33.9 |
| 30 | 19.7 | 50.8 |
Weights in a draft chain add directly in tex, which is why tex is convenient for the roving and sliver arithmetic in Drafting: a roving of 590.5 tex (Ne 1.0) drafted 20:1 gives 590.5 ÷ 20 = 29.5 tex.
Count Is Tied To Twist
Because twist per inch scales with the square root of Ne for equivalent behaviour (recalled relation; see Twisting), a twist figure without a count is meaningless. The overview’s 18-25 twists per inch for warp and 12-18 for weft belong to about Ne 20.
What You Need
- A reel of known circumference (for example 1 m, so 100 turns make 100 m).
- A balance that reads to 0.03 g or better.
- The yarn.
Method: Finding The Count Of A Yarn
Step 1: Reel off 100 m on a 1 m reel, keeping a light, steady tension so the yarn does not stretch.
Step 2: Weigh the skein on the balance.
Step 3: Convert: tex = grams × 10 for a 100 m skein (grams per 100 m × 10 = grams per 1,000 m).
Step 4: Get Ne: Ne = 590.5 ÷ tex.
Step 5: Repeat on three skeins from different places on the bobbin and take the spread.
Worked Example
A 100 m skein weighs 3.10 g: tex = 3.10 × 10 = 31.0; Ne = 590.5 ÷ 31.0 = 19.05. A target of Ne 20 (29.5 tex) is 2.95 g per 100 m, so this skein is (3.10 − 2.95) ÷ 2.95 = 5.1% heavy. The balance must resolve to about 0.03 g to read 1%, since 1% of 2.95 g is 0.03 g.
Common Mistakes
- Comparing Ne across fibers. Other fibers such as linen and worsted wool use different hank lengths in their own counts, so use tex whenever fibers are mixed.
- Reading a higher number as thicker. Higher tex is thicker; higher Ne is finer.
- Weighing damp yarn. Moisture adds weight; condition the sample the same way each time.
- Stretching the yarn on the reel.
Safety
Reeling is done on stopped machinery
A reel with a crank or a motor is a rotating drive with a nip between yarn and reel; do not reel from a running frame, and do not hold the yarn against a turning reel. Take the yarn from a doffed bobbin only (Doffing), and keep the line-shaft stop within reach of any powered reel (Drive System).
What’s Next
- Learn next: Twist Testing — the second property to measure
- Combine with: Thread Quality Control — how count fits the rest of the checks