Yarn count is the first number on every yarn specification and the first input to almost every other yarn test. Tenacity is force divided by count. Pretension for a tensile or twist test is set from count. Fabric construction calculations start from count. A count that is two per cent off quietly corrupts everything downstream.
The skein method looks like simple arithmetic — wind a known length, weigh it, divide — but ISO 2060 is more careful than that, and the care is where results diverge.
What ISO 2060 covers
ISO 2060 determines the linear density (mass per unit length) of yarn from packages by the skein method. It applies to single yarns (spun, monofilament or multifilament), folded yarns and cabled yarns. It does not apply to yarns above 2000 tex, or — except by agreement — to yarns that stretch more than 0.5 % when the tension is increased from 0.5 to 1.0 cN/tex.
The most important sentence in the standard is easy to overlook: it contains seven optional procedures, based on different methods of conditioning and preparation, and because they do not give the same values, the procedure must be agreed by all parties interested in the result.
In other words, "count tested to ISO 2060" is not a complete statement. Which procedure?
Moisture basis: the biggest single source of disagreement
The procedures differ mainly in how moisture is handled. Broadly, a skein can be weighed:
- after conditioning in the standard atmosphere (ISO 139), or
- after oven-drying, with the dry mass then corrected using an agreed commercial moisture regain, or
- without conditioning, with a correction applied.
For a hydrophobic yarn such as polyester, the difference between these routes is small. For cotton, viscose or wool, it is large: these fibres hold several per cent of moisture at standard conditions, and that moisture is in the skein when you weigh it. A spinner weighing oven-dry with commercial regain and a customer weighing conditioned skeins will not agree, and neither will be wrong.
Write the procedure on the report. If the contract does not name one, agree it before the first shipment.
Winding tension
A skein is only as accurate as its length, and length depends on tension. Wind too loose and the yarn does not lie consistently on the reel, so the length actually wound becomes uncertain. Wind too tight and extensible yarns stretch on the reel, so each metre weighs less.
The standard defines the winding tension. In practice:
- Use the reel's tensioning device, not the operator's fingers.
- Check the tension setting when switching between very fine and very coarse yarns.
- Be especially careful with textured and filament yarns, which are the most extensible within the scope.
Reel circumference and skein length
Reels are made with different circumferences — 1 m per turn is the natural choice for tex and Nm, while yard-based reels exist for traditional count systems and for ASTM D1907. The skein length is the number of turns times the circumference. If a laboratory has more than one reel, confirm which one was used and that the turn counter was set accordingly.
ISO 2060 specifies skein lengths related to the linear density of the yarn; other lengths may be used only by agreement, and then must be stated. Shorter skeins are faster to wind, but every small error in length and mass becomes a larger fraction of the result.
Weighing
A fine yarn skein can weigh well under a gram. Use a balance whose readability is fine enough for the skein mass, keep it out of draughts, and do not leave conditioned skeins standing in a room at a different humidity before weighing — they will start exchanging moisture immediately.
Count systems and conversions
The result of ISO 2060 is in tex. Trade still uses other systems, and conversion errors are common.
| System | Type | Relationship to tex |
|---|---|---|
| tex | Direct (g per 1000 m) | — |
| dtex | Direct (g per 10 000 m) | dtex = 10 × tex |
| denier | Direct (g per 9000 m) | den = 9 × tex |
| Nm | Indirect (km per kg) | Nm = 1000 / tex |
| Ne (cotton) | Indirect | Ne ≈ 590.5 / tex |
Direct systems increase with thickness; indirect systems decrease. A "higher count" in Ne is a finer yarn, while a higher tex is a coarser one. When a specification gives a tolerance, confirm whether it is a percentage of the count in the system stated, because a ±2 % tolerance in Ne is not the same band as ±2 % in tex after conversion of rounded values.
Sampling
Count varies between packages more than within them. Wind skeins from several packages across the lot, not several skeins from one cone. Discard the outer layers of each package, which may have been damaged or have exchanged moisture differently from the body of the package. Report the mean and the coefficient of variation between packages.
Before you report
- Which of the seven ISO 2060 procedures was used?
- Conditioned, oven-dry with commercial regain, or corrected?
- Was winding tension controlled by the reel, at the right setting?
- Which reel circumference, and how many turns?
- Is the balance fine enough for the skein mass?
- Were skeins taken from enough packages?
- Is the count system stated, and were conversions done from unrounded values?
Our automatic wrap reels wind ten specimens at once with a programmable number of turns, and our digital count balance calculates tex, denier, Nm, Ne and other systems with statistics. Both are manufactured in our own workshop in Istanbul.