Spirality (also called twist or torque) is the slanting of wales in weft-knitted fabric, especially single jersey. In garments, it shows as side seams that move towards the front or back after washing, and as hems that no longer hang straight.
Why it happens#
Single jersey is an unbalanced structure: all loops are formed in the same direction. Three main factors drive spirality:
- Yarn twist liveliness: a single yarn with high twist has a tendency to untwist. In the fabric, this torque tilts the loops.
- Multi-feeder knitting: a circular machine with many feeders knits courses as a helix, which creates a small course inclination.
- Relaxation: during washing, the loops relax and the torque from the yarn can act fully.
Measuring spirality#
On fabric or garments, spirality is measured after washing:
- Angle: the angle between the wale line and a line perpendicular to the courses (or the fabric edge).
- Displacement percentage: mark a line along a wale over a known length, wash, and measure how far the wale has moved sideways.
For garments, the usual method measures how far the side seam has moved relative to its original position at the hem, as a percentage of the side seam length. Test methods such as ISO 16322 and AATCC 179 describe procedures. Use the method and limits in the buyer's requirements.
Worked example#
A T-shirt side seam is 60 cm long. After washing, the seam at the hem has moved 3.0 cm towards the front.
Spirality = 3.0 / 60 × 100 = 5.0%
Causes and controls#
| Stage | Cause | Control |
|---|---|---|
| Yarn | High twist factor in single yarn | Lower twist where possible; twist-balanced or plied yarns; compact yarn |
| Yarn | Opposite twist direction not used | Alternating S and Z yarns in feeders (on some qualities) |
| Knitting | Loose fabric (long stitch length) | Tighter stitch length for the count |
| Knitting | High number of feeders | Known effect; compensate in finishing |
| Finishing | Fabric not relaxed before setting | Relaxed drying; open-width processing |
| Finishing | Stenter not straightening the fabric | Weft/course straightener; correct overfeed |
| Cutting | Tubular fabric cut on the fold line with the twist | Open width cutting along the wale; mark the wale line |
Fixing spirality in finishing#
Open-width finishing lets the stenter set the courses straight across the width. On tubular fabric, the tube slit line should follow a wale; if the fabric has twisted, cutting along the slit line will cut off-grain.
Garment design and cutting#
- Cut panels on the wale, not along the fabric edge, if the fabric is twisted.
- Side seams can hide or show spirality depending on the style. Garments without side seams (tubular bodies) show twisting as the whole body rotating.
Checklist#
- Spirality tested on bulk fabric after washing
- Garment spirality tested on the first bulk garments
- Yarn twist and count checked when a problem appears
- Fabric relaxed and straightened in finishing
- Panels cut on grain
See the spirality defect guide for troubleshooting a spirality complaint.
Related guides#
- Single jersey fabric: the unbalanced knit structure that makes spirality possible.
- Fabric shrinkage: relaxation and shrinkage, which are measured in the same wash test.
- Bowing and skewing in fabric: course skew and weft distortion, the related faults in finished fabric.
- Fabric shrinkage test (dimensional stability): how the wash test that reveals spirality is set up and read.
- Different types of knit fabrics: which knit structures are prone to twist and which are balanced.
- Cutting room process: how cutting on the true wale line limits garment twist.
Frequently asked questions#
Why does spirality only appear after washing? Knitting and finishing hold the loops under tension. Washing lets them relax, and the yarn torque then tilts the wales.
Does compacting remove spirality? Compacting controls length shrinkage. It does not remove the torque in the yarn, although correct overall finishing reduces the visible twist.
Is open-width finishing always better? For single jersey with a spirality risk, open-width finishing gives the stenter a chance to straighten the courses, which tubular finishing cannot do as well.