Brands that want to avoid waist full and low quality jeans production use our services to buy denim fabrics, and/or finished jeans garments that stand out from their competitors. Backed by a global supply network in regions like Asia, Africa and Mexico.
5 steps how jeans fabrics are made
There are a number of different types of cotton with different physical properties that influence what the denim will look like. It can be hard for the untrained eye to distinguish one kind of cotton from another in a pair of jeans,especially when denim is in its raw state.
One of the most important physical properties of cotton is staple length, which refers to the length of the fiber. The longer the fibers are the better suited to produce high-quality yarns. Generally a staple length of one inch is sufficient. Shorter staple length is generally cheaper and used for mass production.
Another important property is fineness and maturity, which is determined by measuring the air permeability of compressed cotton (micronaire). Using cotton with alow micronaire (mic) count leads to neppy yarn and more waste, as it breaks more easily.
Additionally the strength of the fiber is important as it tells you the maximum load the fibers will hold before they break, which influences the strength of the yarn. This is measured in tensile strength.
And finally the actual color of the fiber is used to distinguish one batch of cotton from another,which is especially important if the cotton will not be dyed before woven into fabric.
The biggest cotton growing nations are: China, USA, India, and Pakistan. Upcoming and noteworthy countries are Brazil, Turkey, and Australia.
Spinning transforms fibers into yarn,the raw material for weaving.
Ring spinning, it was the primary spinning technology used in the denim industry until the 1970's, which makes it the old school way of making denim yarn. It produces a soft and strong yarn with the uneven texture. It requires more production steps to prepare the raw cotton for spinning.
Open end spinning, it produces yarn considerably cheaper and ten times faster than ring spinning.Partly because it spins much faster, but also because it eliminates one of the draw frames and the roving frame. The yarn has a consistent thickness, which gives the resulting denim an even and flat look. And as the fibers are not spun in a parallel direction,open-end yarn is fuzzier compared to ring spun yarn.
Features of spun yarn
Yarn count tells you the thickness of the yarn. It is measured by mass per unit length. (Ne)which is determined by the number of yarn hanks (each 840 yards long)per pound of yarn. The higher the number, the finer the yarn. For robust denim the yarn count is usually between Ne 4 and NE 20. Fabricas listed as 7 x 7 or whatever the vertical indigo warp and horizontal undyed weft yarn is.
The term slubs refers to the regularity of the yarn. Slubs were considered imperfections back in the day. The natural irregularities in the ring-spinning process give denim its desired vertical streaks of slightly brighter yarns as the indigo wears and washes off. Without significant slubs, the texture of denim is flat and it fades more evenly. As brands realized that these irregularities actually made the product more desirable,methods to imitate these slubs were introduced.
Torsion is the measurement of how twisted the yarn is, which determines how dyestuff will permeate it. The more twisted, the higher the torsion, the less indigo it will absorb during the dyeing process. The denim will fade faster when torsion is high. It is difficult to get high-contrast fades because in open-end spinning the dye penetrates deeper into the yarn. Due to the higher yarn twist, ring spun yarn is also significantly stronger than open-end yarn.
Originally the indigo pigment was extracted from dried leaves of the Indigofera tinctoria plant.While the indigo that dyes your denim is still commonly made from powder and water, most denim today is dyed with less costly and more color stable synthetic indigo.
Indigo is a vat dye. The dyestuff needs to be dissolved in water with the help of a reducing agent. , usually sodium hydrosulfite, and the process involves oxidation to fix the color. The indigo molecule is too big for the lymphatic channels of the cotton fiber so it binds only externally.This is known as ring dyeing which gives its propensity for high contrast fades. To get deeper blues the yarns are dipped several times. Synthetic indigo production has less environmental impact.
Weaving is defined as the process of interlacing two sets of yarn at right angles to one another. In weaving the yarns that run in parallel longitudinally are called the warp, also know as ends. The yarns that run across are called the weft, also know as the filling or the pick. It is not in fact the direction that defines what is what. It is the fact that the cross yarn goes over and under the downwards yarns that makes the former the weft and the latter the warp. Traditionally the definition of denim is a twill fabric woven in 3 x 1 construction from indigo dyed warp and undyed weft yarn.
In a shuttle loom the shuttle moves from left to right under and over the warp yarns, which makes for a continues loop in the weft. Creating the finished edges on the fabric. (Selvedge jeans) (150 – 200 picks per minute)
To speed up production, the shuttle-less projectile weaving machine (projectile loom)replaces the shuttle with a small piece of metal that resembles a bullet. The bullet grips onto the end of the filling yarn is shot across the shed carrying the weft with it. At the other side, another projectile is shot back across the shed with a new weft pick. As the filling yarn is cut off with each pick, rather than looped back and forth like in shuttle weaving. The edges of the fabric are frayed and unfinished.
The limited speed of the shuttle puts less stress on the yarn. This gives a softer hand to the fabric.
The most important finishing process of denim is pre-shrinking, also known as sanforization, which is the most important part of securing the dimensional stability of the fabric. The fabric is moistened by steam, An endless rubber belt is squeezed between a pressure roll and a rubber belt cylinder, which makes the rubber belt stretch. The denim is fed in between the cylinders on top of the rubber belt and as the rubber returns to its original length the warp yarns of the denim shrink and the filling yarns are packed closer together. After it leaves the belt it enters the dryer, which locks the fibers in its shrunken state as the moisture is removed.
Skewing is a means of addressing a characteristic of jeans: leg twist, which becomes progressively more noticeable with laundering, as the angular relation between the yarns relaxes. The skewing process compensates for the tensions that cause leg twist, by deliberately skewing right hand twill counterclockwise and left hand twill clockwise.
Heat setting is a vital process for stretch denim. The heat changes the molecular structure of the synthetic fibers and allows the maker to determine the amount of elasticity in the fabric. The longer it is exposed to heat, the less it will stretch.
In singeing, the hairness of the denim caused by excess fibers is removed on both sides by singeing as the denim passes quickly over a flame one side at a time.
Though mercerization is a chemical treatment. It changes the physical appearance of the fiber as well as its properties. The fabric is exposed to a concentration solution of caustic soda, usually under tension. Mercerization opens the fiber and gives it a rounder shape. With the goal of making the surface of the fabric smoother and increasing its luster.
Other finishes may include: Coating, foaming, brushing, calendering, flat optic look finishes, resin applications, and over-dyeing.
Brands that want to avoid waist full and low quality jeans production use our services to make denim fabrics and finished jeans garments to stand out from their competitors.