To test twist, clamp a 10 cm length of yarn, untwist it until the fibers lie parallel, and count the turns; twists per inch equals turns times 0.254, so 20 twists per inch is about 79 turns. Judge warp yarn by its lowest sample, not its mean, and set the twist for your own fiber by spinning trial bobbins at several twist levels and pulling them to break.
Part of Spinning Frame
Counting the twist in a yarn sample, judging its resolution, and using breaking-load tests to find the right twist for a fiber and use.
The Overview’s Method And Its Resolution
The overview: untwist a 10 cm sample and count the turns; multiply by 10 for turns per metre, or by 0.254 for turns per inch. The factor follows from 10 cm = 10 ÷ 2.54 = 3.937 inches, so twists per inch = turns ÷ 3.937 = turns × 0.254.
One miscounted turn on a 10 cm sample is 0.254 twists per inch, which is 0.254 ÷ 18 = 1.4% of the warp floor of 18. On a 25 cm sample (9.84 in) one turn is 1 ÷ 9.84 = 0.10 twists per inch, 0.56% of 18. A longer sample counts more turns (25 cm at 20 per inch is 197 turns against 79) and is slower, so choose by the precision you need: the 10 cm sample is enough to see the slip effect below, the 25 cm one for settling a disagreement.
What To Look For
- Mean twist against the target for the use: 18-25 for warp, 12-18 for weft at about Ne 20 (Twisting).
- The lowest sample. A single soft place in a warp end is a break on the loom. Judge warp by the lowest sample, not by the mean.
- Spread between spindles. Differences between spindles point to tape slip or a sticky bearing (Drive System).
- Direction. Z-twist (the diagonal of the letter Z) is the usual direction for singles; see Twist Direction.
Setting Twist For Your Own Fiber
The overview’s ranges are a starting point. The right twist for your fiber is where strength stops climbing and fuzz is low enough. Find it directly:
Step 1: Spin the same roving on one spindle at four twist levels, for example 14, 18, 22 and 26 per inch, by changing the front roller gear.
Step 2: Pull 20 single ends of each to break on a spring balance and record the force; also record the extension at break against a ruler.
Step 3: Plot mean and lowest against twist. Strength rises, flattens, then falls as the yarn kinks and hardens (Spinning Singles gives the cordage version of that curve).
Step 4: Choose a warp twist on the flat part, with margin above the lowest point that still passes, and a softer weft twist below it.
Step 5: Weave a short trial warp (Warp Tensioning and Let-Off) at that twist and count ends down per hour.
The extension matters on the loom: lifting a warp end for the shed stretches it by a fixed fraction every pick (Shedding), and the yarn must stretch farther than that before it breaks.
What You Need
- Two clamps with a fixed 10 cm gap, one rotating.
- A needle to open the fibers and confirm they lie parallel.
- A spring balance and a ruler.
- A tally or a counter on the rotating clamp.
Method: Counting Twist On A Sample
Step 1: Take the sample from a doffed bobbin (Doffing); discard the first metre.
Step 2: Clamp 10 cm under a very light load so the yarn is straight but not stretched.
Step 3: Rotate the free clamp against the twist while counting turns; probe with the needle until the fibers lie parallel and no more twist can be removed.
Step 4: Convert: twists per inch = turns × 0.254.
Step 5: Repeat on at least five samples from different layers and spindles.
Worked Example
A yarn spun at a nominal 20 twists per inch should show 20 × 3.937 = 78.7 turns in 10 cm. With 5% tape slip the twist is 19.0 per inch, or 19.0 × 3.937 = 74.8 turns. The difference, 78.7 − 74.8 = 3.9 turns, is bigger than a one-turn counting error, so a 10 cm test does detect the slip. A count of 66 turns would be 66 × 0.254 = 16.8 twists per inch, below the warp floor, and that yarn is weft only.
Common Mistakes
- Stretching the sample in the clamps, which changes its length and the count.
- Stopping before the fibers are parallel.
- Testing one place and calling the bobbin good.
- Comparing twists across counts without the count (Thread Count System).
Safety
Test from doffed bobbins, never a moving spindle
Take no samples from a spinning frame; follow the stopping and locking procedure in Doffing. A needle used for untwisting punctures skin; clean any puncture and keep it covered. Powered test rigs follow the stop rules in Drive System.
What’s Next
- Learn next: Warp Tensioning and Let-Off — what the warp’s strength has to withstand
- Combine with: Thread Quality Control — how twist fits the other checks