Sewing thread is a small part of the garment cost but a large part of seam performance. A thread must be strong enough for the seam, sew well at production speed, match the fabric color and survive washing and wear.
Common thread types#
| Type | Construction | Typical use |
|---|---|---|
| Spun polyester | Staple polyester fibers spun and plied | General purpose seams on knits and wovens |
| Core-spun (poly/poly or poly/cotton) | Continuous filament polyester core wrapped in staple fibers | High-strength seams, denim, workwear, high-speed sewing |
| Textured (bulked) polyester or nylon | Crimped continuous filament | Overlock loopers and coverstitch covering threads; soft, stretchy seams |
| Continuous filament polyester or nylon | Smooth filament, often bonded | Heavy products, bags, footwear, some outerwear |
| Cotton | Natural fiber, mercerised | Garments that are garment dyed; decorative work |
Ticket number and size#
The ticket number is a commercial size label for thread. For most synthetic threads it is based on a metric count system, and a higher ticket number means a finer thread. Different manufacturers and fiber types use different ticket systems, so a Tkt 120 from one thread type may not be the same size as a Tkt 120 of another.
Typical choices (starting points only):
| Application | Typical ticket |
|---|---|
| T-shirt overlock and coverstitch | 120 to 180 (textured for loopers) |
| Shirts, blouses | 120 to 150 |
| Trousers, chinos | 75 to 120 |
| Denim seams and topstitch | 30 to 75 |
| Decorative topstitch on denim | 20 to 36 |
Check the thread maker's recommendations for the fabric, seam and needle.
Matching thread to the job#
Fabric weight#
Heavier fabrics need stronger, coarser threads. Very strong threads on light fabric cause puckering and larger needle holes.
Seam type and stress#
Seams under stress (crotch, side seams on fitted garments, workwear) need stronger thread. The seam should be weaker than the fabric so that, if it fails, it fails at the seam rather than tearing the fabric. See seam strength.
Stretch#
Knit seams need stretch. Use suitable stitches (overlock, coverstitch) and, for loopers, textured threads.
Needle size#
The thread must fit the needle eye and groove. Too thick a thread for the needle causes breakage and skipped stitches. See sewing needle selection.
Dyeing and washing#
- Garment-dyed products need thread that dyes with the fabric (cotton on cotton garments) or deliberately contrasts.
- Garments with enzyme or stone washes need threads that withstand the process.
- Check color fastness of dark threads on light fabrics.
Color matching#
Match thread color under the buyer's specified light source. Thread appears darker in a seam than on the cone. Record the thread shade reference in the bill of materials.
Thread quality problems#
- Weak places or poor evenness: breaks at high speed.
- Poor lubrication (finish): needle heat, breaks and uneven stitch.
- Twist imbalance: loops twist, causing skipped stitches.
- Wrong package type: poor unwinding at speed.
See thread breakage for troubleshooting.
Specifying thread#
- Fiber and construction (spun, core-spun, textured)
- Ticket number or size, by operation
- Color reference by fabric color
- Package length (meters per cone)
- Consumption per garment by type. See thread consumption
Related guides#
- Stitch types: the stitch types that decide how much and which thread is used.
- Stitch density (SPI): how stitch density changes seam strength and thread use.
Frequently asked questions#
Why use different threads for needle and looper? Needle threads need strength and smooth passage through the needle. Looper threads in overlock and coverstitch mostly cover the seam edge, so soft textured threads give better coverage and stretch.
Does a stronger thread always make a better seam? Not always. A very strong thread on a light fabric can make the fabric fail before the seam, and needs a larger needle, which creates bigger holes.