Yarn Thickness

A merchandiser, let’s call her Kim, in a sourcing office has received a request from her buyer to find a fabric with following specification: cotton chino CM20 × CD16, 120 × 68, 58". Although this is quite a common type of fabric, Kim is confused. She knows what these numbers mean but cannot get a clear picture of this fabric. So she has to call several mills, requesting for cost details and swatches. Kim has no idea about the fabric until the mills respond. And the only way that she can verify the information is through crosschecking with other mills and the buyer. It is a time consuming task. This chapter is about the basics of fabric, yarn count, thickness, and density, which alter its appearance and function.

During my business trip to the States this autumn, I had a free Sunday in my schedule. Not wanting to golf or bother my staff in New York branch office, I decided to go shopping. The place I chose was Woodbury, a very popular outlet that sells top designer brands like Prada, Salvatore Ferragamo, and Gucci. Among its 300 stores, Polo Ralph Lauren was the most crowded.

Polo’s chino pants have been one of its best sellers for more than 20 years. Chino pants are made of cotton twill fabric that Britain once had exported to India and China. Chinos became famous after the American soldiers wore them as uniforms during the First World War. Its name actually means Chinese in Spanish.

The original Chinos seem to have been woven with twisted yarns. Today, Chinos are made from CM20 × OE CD16, 120 × 68 58" fabric. CM stands for combed and CD stands for carded. Both indicate how much the thread has been brushed. The plucked cotton is just a ball of fluff called lap. This is made into a sliver, a rope-like strand. Roving makes cotton into thinner strands and it is the last stage before cotton is spun into a thread. These steps of cotton processing can be described simply-endless brushing. Cotton fibers are scattered in all directions so they need to be aligned. Combing is a more intense version of brushing than carding. The more cotton is combed the finer it becomes.

Cotton fibers are short, about 2.5cm long. These fibers are held together when they are in the form of a lap but become loose as they are combed. In order to spin them into a long thread, the fibers have to be twisted. Finer thread requires more twisting as the force of friction becomes less. The number of twist is proportional to the fineness of yarn. If a yarn gets finer by 4 times, it needs to be twisted twice more. If it gets finer by 9 times, the twisting is thrice more.

If the yarn is twisted more than the above proportion, it becomes shorter and stronger through turning and bending. This type of thread is woven to make fabric with a grainy and uneven surface called crepe. The long chain of 3 billions pairs of DNA nucleotides are placed in tiny cells through this physical aspect of intensified twisting.

The cotton chino fabric has another abbreviation: OE. This stands for open end, a method of yarn spinning that revolutionized the production rate. Sliver skips roving processing and is directly made into a thread. This method, however, is limited to thick yarns with the yarn count less than 16s. The actual limit is 20s, but OE is not usually used for this yarn due to cost inefficiency. The regular method called ring spun (RS) is applied for making finer yarns in 20s and above. Sometimes, RS is used for 16s to make premium denim. OE yarns for 16s and below are cheaper than RS yarns but they are bulky and harder in quality.

The relationship between CM/CD and the yarn count can be explained as above. The limit is 30s. CM is for fine and expensive yarns with yarn count above 30s. CD is for those under 20s. There are some exceptions to this rule for CD 40s and Cm 16s but the limit is kept for cost efficiency. I have never seen other exceptions beside these while working with textiles for 22 years.

Mixing raw cotton is another matter to be concerned about. Cotton varies in its grade according to the length of its fiber. Fine Egyptian cotton is 1cm longer than American cotton. Longer fibers with more friction are spun into longer yarns with less twist and softer touch. So good-grade cotton like Egyptian cotton is used to make finer yarns. It would be nice to make yarns with 100% top-grade cotton but the price has to be kept reasonably high. Raw cotton mixing plays an important role to balance both quality and cost. Yarns in 30s and 40s count have similar price because their cotton mixing proportion is similar. From 50s and on, however, the price suddenly jumps because the proportion of good-grade cotton has to be increased drastically.

In the measurement of chino fabric (CM20 × CD16, 120 × 68, 58inches), 120 × 68 is the scale of density. But what does it really signify? The numbers 120 and 68 indicate there are 120 warps and 68 wefts in one inch or 2.54cm. Since fabric is 58inches in width, the total number of warp is 6960.

Likewise, it is difficult to imagine how thin or thick a yarn is with the numbers of yarn count in 20s and 100s. The numbers are meaningless as 2.5 million light -years. The thickness of a yarn, like a person’s waist, could be measured in circumference but then the number would be too small. So there are two special methods for measuring yarn thickness or yarn count: fixed weight and fixed length.

Fixed weight, or English yarn count, is the most common method used for all types of yarns made of twisted spun fibers. 1s in English yarn count equals to 1 lb of yarn measuring 840yd. So 40s yarn is 1 lb of yarn measuring 33,600 yards in length. So thinner yarn has bigger yarn count number.

The length of 1 lb yarn in 40s is the approximate distance between my home to my office. But how thin is it? 40s yarns are usually used for shirts and rarely for pants because they have weak tearing strength. 30s yarns are made into heavy shirts, light pants, or blankets. Twill pants are made of 20s yarns and canvas fabrics are made of 10s yarns. Sometimes, yarn count is mixed to improve fabric touch. Fabrics with 60/3s yarn count are truly soft although the yarn thickness is equal to 20s. Yarns in 50s and above produce lawn, the fabric used for making fine summer blouses. Cotton woven fabric with the thinnest thread has 100s yarn count. These are used to make high quality lawn, chiffon, and voile.

The other method for measuring yarn count is fixed length method. It is used to measure thickness of filaments in fabrics like polyester, nylon, and silk. The unit is denier: 1d equals 1g per 9,000m. So 9,000 meters of a yarn with 70d is 70g in weight. Unlike English count, yarn gets thicker and heavier with increased denier.

By the way, how is yarn count checked? Complicated equipments are unnecessary. Even a test lab like FITI checks yarn count simply by using a scale and a ruler.

There were two different methods of yarn count for carded wool and combed wool. Combed wool yarn count was the same, 1s equaling 1 lb of 560yd, but carded wool yarn count slightly varied by region. For example, 1s was 1 lb of 256yd in Yorkshire whereas it was 300yds in Philadelphia. These different yarn counts were combined into fixed weight method in the metric unit called Nm. 1 Nm is 1kg of yard in 1km length. The number of yarn count gets higher for finer yarns.

The easiest way to understand Nm count is by converting and comparing it with the English count. Since wool yarn count is about 1.7 times bigger than that of cotton, dividing it by 1.7 results a number that can be compared with cotton yarn count. So when a salesman at a suit says 120s for a suit, the number is actually 70s. For acrylic, 36/2 is the most common yarn count. This is equal to 10s in cotton yarn count.

For synthetic yarn count, 135d equals 40s in cotton yarn count. This is the famous peachskin faille. The most commonly used synthetic fabric has yarn count of 70d for nylon and 75d for polyester. The nylon lining called taffeta has 70d yarn count. 75d polyester comes in CDC, tissue faille, dobby, and GGT used to make blouse. The next common yarn count in synthetic fabric is 150d, which is often combined as weft. Thicker yarn that comes in 150d × 150d or 300d × 300d is moss crepe.

For thinner yarns, 50d/300t is common in nylon used for high density down jacket fabric. 300t here indicates the sum of density in warp and weft. DuPont’s down jacket fabric comes in 40d/330t. With the recent trend for the ultra light fabric, there are fabrics even in 30d and 20d. Mono-filas in 20d are almost as thin as dragonfly wings and have long single threads that look like the strings of a fishing rod.