Indigo dyeing for denim

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The concept of creating one’s own fade is mostly relevant for raw unwashed dry denim fabrics, and will only be a successful project through months of wear before the first wash. Just like leather has an ability to get a beautiful patina through time, denim, almost more than any other fabric in the world, only gets more beautiful as it ages.
We’d like to dig even deeper into how denim evolves like it does and as to why so many people swear to wearing a pair of jeans for several months before washing them. We know that to some, this might be too specific. But, bear with us as we go deeper into the process of indigo dyeing when making a denim fabric and try and explain how this actually pans out.

the indigo dying range
The process of creating a denim fabric primarily consists of five major steps. Harvesting the cotton yarns, yarn spinning, indigo dyeing, weaving and fabric finishing. After the cotton has been harvested and the cotton yarns spun, it consists of lots of threads of cotton spun yarns, ready to go into the indigo dyeing range and into the actual indigo vat.
What was traditionally done by hand and referred to as “hank-” or “skein dyeing” has now turned into a more industrialized process domained by two different methods for indigo dyeing. The slasher dyeing method and the rope dyeing method, whereas the slasher dyeing method is the youngest and less labor-intensive method of the two.
Livid consequently uses fabrics that are made in Japan, whereas our main suppliers are the two renowned mills Kuroki and the artisanal mill Nihon Menpu. Both who still holds true to the old dyeing method invented in 1915 and today referred to as the rope dyeing method.
The method of rope dyeing simply consists of bundling together up to two dusin ropes of 380 to 420 cotton spun yarns before they are warped onto a beam prepared to enter the dyeing range. From the warping beam and just before entering the actual indigo vat, the cotton ropes are transported through cleansing rinse boxes, that removes natural oils and impurities that might cause difficulty for the indigo dye to bind itself to the cotton fibers.
The ropes of cotton spun yarns are then transported into the actual indigo baths for up to 30 to 60 seconds before they are exposed to air and oxidation for up to 60 to 180 seconds.. This process consists of up to as many as 12 indigo dye boxes whereas each bath is followed by additional oxidation throughout the range.
After being dipped in several indigo baths – usually an average of about six dips – the rope yarns are transported through up to three washing boxes that removes excess indigo dye from the rope yarns. Lastly, during the final steps of the dyeing range, a softener is added in the last box to ease the opening of the ropes making them easier to separate. The ropes are then dried and separated onto a new warping beam ready to go through the sizing process. Whereas the yarns are encapsulated with a protective starch to prevent them from breaking during the weaving process. The amount of starch encapsulated around the yarn combined with the finishing process will determine how stiff the finished fabric feels.
Now, it is said that when using particularly rope dyeing as a method, the rope yarns are dipped in such short intervals that the indigo molecules don’t have time to fully penetrate the yarns. And that this in turn, will only create outer layers of indigo, leaving the raw cotton core undyed.
While this may be a contributing factor as to how a pair of raw jeans evolves like it does, it also has to do with the fact that the indigo molecules simply are too big to penetrate through the lymphatic channels of the cotton fibers.

the indigo dye
Indigo in its raw form is water-insoluble. Therefore it needs to undergo a chemical change into a water-soluble form often called indigo white. A vat dye, which is a water-soluble dye where a reducing agent is applied into the bath, dissolves the indigo to a soluble form enabling it to attach to the cotton fibers. After the indigo is dipped into the bath and comes back in contact with the atmospheric air, the indigo molecules oxidizes back into its insoluble blue indigo compound and binds itself to the cotton fibers. Since indigo has such a low affinity for cotton, a deep indigo colour is only obtained when dyeing and oxidizing are repeated several times.

After the indigo dyeing process and the third step of creating a denim fabric is finished, we have our indigo dyed warp yarn on a beam roll ready to be interlaced with the weft. Heading straight to the weaving of the actual denim.

the fading process
Now, the indigo actually “sits” on top of the cotton fibers. When wearing your jeans, and the fabric is exposed to friction, the colour will slowly tear off layers and layers of indigo dye, eventually causing the raw white cotton core of the yarns to appear. Leaving a beautiful contrast fading, such as whiskers and honeycombs on the upper thighs and behind the knees and generally on the most exposed areas.
Now it is said that when you give your jeans the first wash, you stop the process. Therefore you would like to tear off as much colour as possible before giving your jeans the first wash. After each wash your jeans will actually fade more, and create a beautiful look, for which no other industrialized wash can come close to compare with.
To some starting fresh with a brand new pair of raw denims, and breaking them in, is making art. To others it’s a process that gives the ability to make the jeans look exactly how you want them to look. You do not need to wait one year for a good result. But be patient, wait until you are satisfied with how they look, and then, wash them and perpetuate the result.