How to Make DenimRAW COTTON
Our globally sourced and expanding inventory of raw cotton sustains our denim production
The raw cotton quality can make or break the outcome of the denim. We have established an enormous raw cotton warehouse of approximately 5500 square meters in our Sanwa Mill, to have a secure supply of high-quality raw cotton. We stock a large amount of carefully selected raw cotton from the world's major cotton-producing countries such as the United States, Australia, and Brazil. The raw cotton is compressed and packed in units of 225 kg per bale, and the warehouse holds roughly 20,000 bales. Convert that to pairs of jeans, it would estimate to roughly 5,500,000 pairs.
Bales of raw cotton are first carried over to a room to be unpacked by hand. Then they are loosened through a machine dedicated to a process called mixing. Mixing is a process where according to the desired type of denim fabric, raw cotton of different origin is blended while dirt and leaves thoroughly removed. The cotton fibers are untangled one by one and placed parallel and bundled into what is called a sliver and then sent to the spinning mill.
How to Make DenimSPINNING
Precise movement that transforms raw cotton into yarn
Kaihara completed a spinning line at the Kisa factory in 1991 and established a fully integrated production line. Here, the latest spinning machines are in full operation for 24 hours. The sliver made from the raw cotton is first processed through a machine called a drawing machine to achieve a uniform thickness. It is then put through a roving machine to be stretched whilst being twisted to be made into roving. Then, a series of large-scale spinning machines are used to spin a particular thickness of the yarn.
There are two types of spinning methods that we practice at Kaihara. Ring spinning that twists through a rotating metal ring and open-end spinning that twists in a vortex of air. The two different spinning methods enable us to create a wide variety of yarns to be used accordingly to create the desired fabric. The spinning machine is strictly automated by a computer, which completely prevents defects. Also, constant adjustments keep the factory at a consistent temperature and humidity to improve the quality of yarn.
How to Make DenimDYEING
An enchanting gradation achieved by indigo dyes
It's fair to say the essence of Kaihara is our dyeing process. The spun yarn goes through a process called warping before the dyeing process. The equipment and machines used in this process of bundling 600 to 900 raw yarns in a rope shape to the length of about 6000 yards were independently developed by Kaihara. After warping, the next step is the process of rope dyeing which is unique to making denim fabrics. Using the rope dyeing machine which Kaihara succeeded in developing for the first time in Japan, we dye the raw yarn with indigo dye.
The raw white yarn passes through an indigo dye bath and is then squeezed with a roller. At first, it has a bright green color, but then after being raised and in contact with air it oxidizes, gradually turning into the indigo color. Different shades can be expressed by adjusting the indigo dye formulation and air exposure time, but this requires skilled expertise. Moreover, rope dyeing is characterized by only dyeing the surface without the core of the yarn being dyed. This process creates the color fading distinctive to denim.
How to Make DenimWEAVING
Making full use of new and old looms and weaving unique denim fabrics
The indigo dyed yarn is sent off to the weaving process. A number of old-fashioned shuttle looms are in operation at Kaihara's upper and lower factories. Through proper and careful maintenance, we have been able to continue their use. Since the shuttle loom is an old machine, it has poor stability and slow speed in fabric weaving. However, the value lies in the unique unevenness and tasteful expression it gives to create Selvedge Denim, which newer looms cannot achieve.
As well as shuttle looms, we also have many newly innovated looms in operation. In order to weave a variety of denim fabrics, we have different looms to meet different needs, such as the projectile loom that supports heavyweight denim with heavy count yarn, and a high-speed air-jet loom for fine count denim. This way, we continue to create new fabrics intertwining new and old technologies, supporting the future generation of Kaihara's manufacturing.
How to Make DenimFINISHING
Final touches after strict inspection
The woven denim fabric is checked through a thorough inspection process to check the quality and whether it meets the required standards. As soon as a problem is found, it is feedbacked back to the previous site to make necessary corrections. This close and efficient processing is the advantage that integrated production offers. Denim fabric that's cleared the inspection is sent to the final process called finishing. Here, several final touches are carried out to prepare for shipment, such as singeing to eliminate surface fuzz, starching to add stiffness, pre-skewing to prevent fabric twisting in wash cycles, and pre-shrinking to prevent further shrinkage upon washing.
Denim fabric that has gone through this finishing process is then, returned to another final inspection. Expert staff carefully examine six criterias: tear strength, color difference (color unevenness and variation), degree of skew prevention, tensile strength, stiffness (texture and softness), and wash shrinkage with inspection equipment. Only after passing all of the final inspections can a denim product be shipped out.