It's fair to say that the spinning technics back then were not fully developed. All denim reproduction brands are trying to replicate the irregularity by lots of different methods, mostly computer-regulated ways. But I came up with an unprecedented way to do it.
When TCB produces a new fabric, they always choose the right cotton breed and its blend ratio. This time, they have made a new fabric from a scrap fabric of 1910 woven by Amoskeag mill, later replaced with the famous Cone mill as you know. Having a glimpse at the fabric, they immediately noticed the strong irregularity on each yarn, by far the strongest slubby and neppy denim compared to numerous vintage Levis jeans. So, it was this slubbiness that was the key to reproducing this fabric.
Usually, when making the irregularity of the threads, they change the thickness of the threads and use that one thread for the whole fabric. But no one has not made it one step further about this. Of course, the quality of cotton from the old days was unstable and poor, but the spinning as well for sure. So this time, TCB has decided to use two different threads spun by two different spinning indexes: 80% hard-spun, and the rest of 20% have half the spinning index used for the said hard-spun.
Of course, they wanted to make perfectly spun, perfectly woven, perfectly dyed fabric back then. Still, with the benefit of hindsight, the spinning was unstable, so it's like not the irregularity on the thickness of the threads. Still, the irregularity of the spinning index played a significant role in vintage fades. If the spinning index is different, the dyeing absorbency differs even on a thread so that they'll develop the most natural irregularity of indigo dye too. The cotton used is EMOT cotton (East Memphis, New Orleans and Texas) blended with some Pima cotton from the state's southwest. Pima gives a nice and creamy brownish tinge to the threads, and this blend was a perfect balance. This fabric is 10.7oz
Sakamoto Denim did the dyeing process in Okayama. Natural indigo rope dye requires some confidential know-how so that we couldn't even get in the factory for photo shooting. As far as we know, only 1 or 2 factories in Japan can do it.
The threads of this natural indigo fabric go into the pool of indigo 16 times. Our aim on the new fabric is strong stubbiness and strong irregularity on the surface. To achieve that, they need to speed down the rotating speed of the shuttle as much as possible.