Coats puts size first: the thread has to be thick enough to hold and fine enough to bury. Fiber and construction decide whether it stretches with a knit, withstands a wash, or sheds lint into the discs. Buy the job, not the pretty spool.
Jobs: all-purpose, serger, topstitch, embroidery, bobbin
| Job | What it is | Where it fails |
|---|---|---|
| All-purpose | Home lockstitch thread, usually a mid Tex (often around Tex 24 to 35 in the Coats apparel charts). | Too fine for visible jeans topstitch; too coarse for chiffon if you force a heavy spool. |
| Serger / overlock | Often a finer cone. Coats apparel charts put looper thread around Tex 18 (Ticket 180) with needle thread Tex 24 to 30. | All-purpose spools on a serger run out and throw twist into the loopers. Threads Magazine: match fiber and weight to machine and cloth. |
| Topstitch | Heavier, for a drawing on the face. YLI charts 30/3 around Tex 50, jeans stitch much heavier. | A universal needle’s small eye will shred it. Use a topstitch needle (long eye). |
| Embroidery | Usually rayon or poly around #40, Tex ~24 on the YLI chart, meant to sit on the surface and shine. | Poor seam thread. It is not built as a construction ply. |
| Bobbin | Can be the same as the needle thread. Dedicated bobbin thread is finer, for embroidery density or a softer wrong side. | A much finer bobbin with a heavy needle thread will fight the tension calibration of a home machine. |
Textured thread (woolly nylon, fluffy looper thread) lives in serger loopers, where it covers the edge. It does not belong in a lockstitch needle. Nylon filament is strong and slightly elastic; it is common in fine serger cones and in some invisible-stitch applications. Silk is a luxury construction and basting thread, fine, with little lint when it is well made.
Fiber
- Polyester: the default all-purpose. Strong, some give, colorfast, unhappy at a too-hot iron.
- Cotton: locks into a cotton weave, takes a press, can rot or weaken with age. Count systems (50/3, 40/3) still label a lot of quilting cotton thread.
- Cotton-wrapped polyester. Coats Dual Duty’s old idea: poly core for strength, cotton coat for the lock and the iron.
- Silk: fine, expensive, beautiful in a tailor’s basting or a silk cloth. YLI lists filament silk from about Tex 12 (#100) up.
- Nylon: strong, some stretch, can be harsh on the skin in a garment seam; common in serger and upholstery.
- Textured / woolly: bulk without weight, for loopers.
Weight systems: Tex, wt, ticket
Coats: numbering is either fixed-weight (the yarn gets finer as the number goes up: cotton count Ne, metric Nm) or fixed-length (the yarn gets heavier as the number goes up: Tex, denier, dtex).
TexWeight in grams of 1,000 metres. Tex 40 means 1,000 m weighs 40 g. Larger Tex is thicker. This is the honest system.
Weight (wt)A commercial label, usually inverse: 50 wt is finer than 30 wt. Quilting cotton 50/3 is a common all-purpose. Do not assume one company’s 50 wt equals another’s without a Tex.
TicketA manufacturer’s reference. Higher ticket is finer. Coats: to convert Tex to a ticket number, divide 1,000 by Tex and multiply by 3. Ticket numbers are not interchangeable across fiber types. Ticket 40 cotton is not Ticket 40 corespun.
Coats conversion (from their table):
| Tex | dtex | Denier | Nm | Ne c | |
|---|---|---|---|---|---|
| From Tex | × 10 | × 9 | 1000 / Tex | 590.54 / Tex |
Worked ticket numbers from Coats’ own examples:
| Tex | Ticket (their calc: 1000/Tex × 3) | Notes from Coats |
|---|---|---|
| 40 | 75 | Cited as (1000/40 × 3) |
| 60 | 50 | |
| 80 | 38 | |
| 100 | 30 |
Apparel lockstitch charts on Coats’ site often pair Tex 24 to 30 with Ticket 120 to 100 and Tex 40 with Ticket 80. Those product tickets are in the same neighborhood as the formula, not always identical. Ticket is a commercial label. When a cone prints both Tex and ticket, believe Tex for thickness.
YLI’s “Thread of Truth” chart, as a second citation for home spools:
| Example thread | Count | Tex (YLI) | Needle they list |
|---|---|---|---|
| Light cotton / silk #100 | 70/2 to #100 | 11 to 16 | Universal or microtex 70/10 |
| All-purpose poly, 50/3 | 50/3 | 35 | Universal 70/10 to 80/12 |
| 40/2 | 40/2 | 27 | Universal 70/10 to 80/12 |
| 40/3 | 40/3 | 40 | Universal 80/12, sharp 80/12 |
| 30/3 topstitch | 30/3 | 50 | Topstitch 90/14 |
| Rayon/poly #40 embroidery | #40 | 24 | Embroidery 75/11 to 80/12 |
Needle pairing
SCHMETZ: choose needle size by thread thickness, needle type by fabric. The eye has to be large enough that the thread is not sawed on every stitch.
| Needle | Point | Use |
|---|---|---|
| Universal | Slightly rounded | General wovens and some knits. The default 80/12 with all-purpose thread. |
| Microtex (sharp) | Slim acute | Silk, microfiber, coated cloth, precise topstitch on fashion fabric. |
| Stretch | Medium ball, special eye and scarf | Highly elastic knits, lycra. Prevents skipped stitches. |
| Jersey (ballpoint) | Medium ball | Knits. Pushes loops aside instead of cutting them. |
| Jeans | Medium ball, reinforced blade | Denim and dense wovens. Less deflection, fewer broken needles. |
| Topstitch | Slightly rounded, elongated eye (2 mm in all sizes on the 130 N) | Heavy, multiple, or poor-quality threads. The long eye is the point. |
Worked example: jeans topstitch
All-purpose Tex ~30 in an 80/12 universal will sew the seams. For the face rows, a 30 wt / ~Tex 50 topstitch thread in a 90/14 topstitch needle (YLI’s pairing) is the combination that does not shred. If you put the heavy thread in a universal eye, it will glaze, skip, and dump fuzz in the tension discs. That is the needle, not your tension dial.
All-purpose versus quilting weight
YLI: in quilting-weight language, 50 wt is the piecing workhorse (flat seams); 40 wt is the quilting that shows. All-purpose polyester is the garment spool: wash, give, one cone for seams. Do not treat those as one product. The comparison is all-purpose vs quilting thread. Search kits (not our stock): all-purpose, quilting.
When cheap thread fuzzes the tension discs
Tension discs are two plates that squeeze the upper thread. Lint between them keeps the plates from closing. The Sewing Machine Man: compacted lint or shredded thread wedged in the upper discs gives you a zero-tension condition, loops on the underside. The same crud in the bobbin-case discs gives you eyelashes on top. Cheap, short-staple thread sheds that crud on purpose. It is not mysterious.
If a bargain spool feels dusty on your fingers, it will felt the machine. Signs:
- A grey beard of the thread color on the tension assembly.
- Tension that “randomly” dies after a few seams.
- Thread that shreds at the eye and leaves a tail in the discs.
Fix the path, then replace the spool. Raise the presser foot so the discs open, floss with a strip of tightly woven cloth or a bill, and brush the bobbin case. Do not oil the discs. Then buy a thread that does not manufacture lint as a by-product. Construction thread is a tool. Tools that fill the works with dust are the wrong tools.