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3sixteen’s Tour of Kuroki Mills: Denim From Start to Finish

New York’s 3sixteen has long had the honor of being one of the only small raw denim companies with their own proprietary fabric. They developed their 14.5oz 100x selvedge denim with Japan’s Kuroki Mills and have used it for nearly four years across their entire line.

3sixteen’s owners Andrew Chen and Johan Lam recently visited Kuroki in Okayama, Japan and documented the dyeing and weaving process on Instagram (be sure to follow them if you don’t already) and with photographer Martin Kirby. VSCO featured some of the photos from their trip on their blog earlier this week, we’ve collected 3sixteen’s text and images to tell the story of how Kuroki weaves their denim.

We flew to Okayama for the day to visit Kuroki Mills. This is where all of our denim is woven for us from start to finish.


Kuroki is one of two mills in Japan that indigo dyes their thread in-house from start to finish under one roof. The process begins here, where cotton warp yarns are run through a machine to prepare them for rope dyeing.





500 cotton threads combine to form one rope, which is then spun onto a big roller that you’ll see in the next photo.


Each of these rolls has one continuous rope of warp threads wrapped all the way around.


Here are the ropes coming out from their first indigo pass. Remember the photo we took of the 500 yarns passing through the machine? Each rope (which looks like a belt) consists of 500 warp yarns condensed together, and 8 ropes get run through the dyeing machine at once.


Note how the threads are a bright green once they come out – this is because indigo needs time to oxidize and turn blue. The row behind the first pass has already started to darken.



It’s impossible to capture the entire system in one photo, but each continuous rope travels up and down on the rollers anywhere from 7-10 times in and out of indigo reservoirs. Indigo color depends on the type of cotton thread used, concentration of indigo, number of dips, and duration of oxidation in between dips. All of these factors can be controlled with incredible accuracy by Kuroki.


After the last indigo pass, the ropes go through heated rollers to be dried out and are then laid down into carts.



Each cart is brought into the next room, where a single rope is run through a machine to separate out all 500 warp threads onto a wide roll. This process requires great attention to detail; if a single thread snaps during this process the machine must be stopped and the operator must trace the broken thread all the way back to the rope to reconnect it.


The warp threads needed to be separated out by the previous machine so that they could be steamed and starched, as you see here. When they exit the machine, the yarns have a dry, almost paper-like hand. This must be done to allow them to run through the shuttle loom easily.



This is where the magic happens. All denim weaving happens in a separate building that houses two large rooms full of vintage Toyoda shuttle looms that run all day long. The sound is quite deafening; you don’t realize how loud the machines are until you step outside and realize that your ears are ringing.


When we booked our trip to Kuroki months ago we were given no guarantee our fabric would be on the machines on the specific day we would be visiting (and understandably so). After entering the room and walking around for a bit with our jaws agape, we were pulled over to one machine and told excitedly that our 14.5oz 100x denim was indeed being woven.

Warp threads enter the back of the loom off the roll…


…and woven 100x selvedge denim comes out on the other side.






Unfortunately, because we spent so much time at the dyeing and weaving plants, we were unable to see the sanforization and finishing process. Even at rest, though, the facility was impressive – and once again we were reminded of how much work goes into every yard of fabric that is woven for us.


Every inch of finished denim is visually inspected to make sure there are no flaws or defects in the weave. The machine passes the entire roll of denim over a lightbox, and the inspector stops it to trim loose threads or jot down any issues he notices onto a chart.






That wraps up our Kuroki tour – we hope you enjoyed the photos. The finished denim in this photo is our 15.5oz raw indigo (the fabric we used on the 30BSP and our anniversary jeans). The hand belongs to Ono-san, the man responsible for bringing our creative ideas to technical fruition with the mill.

It takes a lot of machines to make denim, but it takes a lot of skilled people too.

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