Denim 101 with W.O.L.F.

A couple of weeks ago, I took a lovely trip out to North Carolina to go back to school at White Oak Legacy Foundation for the launch of Denim 101. It felt amazing to be a student again, learning from top industry veterans about the construction and making of denim and jeans, all while being engulfed in the history of one of the world's most significant textiles manufacturing hubs. From fibre production to denim finishing, W.O.L.F. covered it all and together, we wanted to share the highlights and practical takeaways with you. The more I learn about the supply chain, the more I learn about how many supply chains are within one supply chain, which you can see in Supply Chain 101. Denim and jeans are also very unique (which all of us denim heads can agree on), meaning knowing the extra efforts to make blue jeans is essential. The class was divided into two days; the first day gave attendees an overview of textile production by Suzette Mchugh, with the second day specifically focussing on denim with Bud Stickland and Denis Scheer. Day one started off with textile's natural beginnings: natural fibres and cotton. Now I won't bore you by listing off natural fibres (click here if you want the list), but it is important to note the different cotton types. You have Extra Long Staple, Long Staple, Upland Staple, and Short Staple fibres, which all have different qualities associated with each. Extra Long Staple fibres are the highest quality fibres, with short staples being the weakest. For any of you natural fibre geeks, 1,5" is the optimal staple fibre length. We also covered the complete supply chain of producing and extruding synthetic fibres, which are largely used in denim today, but I'll let those who wish to know more about synthetics sign up for W.O.L.F.'s next course.


Yarns, in particular, have been an area I have wanted to understand better as the race to trace back our fibres to farm or production level is on. Once we have our bales of matted clumps of staple fibre, it's time to "open" (separate) the staple fibres into loose fibre sections. But, cotton comes in different shapes and sizes and to produce quality yarn, we need to ensure uniformity. To do so, at least 56 bales of cotton are laid down to create your cotton mix. The more bales, the more uniform the yarn. However, bale sources can get mixed very easily, making traceability efforts much more challenging. After opening and cleaning, the next step is carding, which turns the loose fibres into a continuous untwisted strand called a sliver. Next up is Carding, where we combine several slivers together to improve uniformity. This would also be where you blend multiple fibres together. Roving to further align and reduce the sliver size and weight is next, with Spinning as our final step to draw down the roving to the final yarn size. In denim, we have open-end Spinning and ring-spun yarns, which you can find a brief overview of on Supply Chain 101 here, but stay tuned as I work with W.O.L.F. to give you all the details, so you know which yarn type you are looking for. But, I am dying to share how we calculate yarn size. Denier is a fineness measurement used for synthetic fibres calculated based on grams in 9000 meters of that yarn. For example, 1 Denier = 9000 meters of yarn weighing 1 gram. A Denier of 150 would mean 9000 meters of yarn weights 150 grams. On the other hand, we have the Cotton Count, which measures the fineness of a yarn based on how many times it takes 840 meters of yarn to equal 1 pound. Kind of an odd measurement but 840m it is!


Now that we have our yarns, it's time to get weaving. Your fabric is the main component of a jean, which is why a good fabric design can make or break the best fit or style in an instant. When designing a fabric, the key considerations are fibre content, yarn parameters, weave/construction (2x1, 3x1, etc.), final performance requirements, aesthetic preferences, finishing options, costs, equipment availability, supply issues, delivery and logistics. Once we have your final fabric, we can measure its density by calculating the Ends/inch X Picks/inch (or Warp yarns/inch X Weft or Filling yarns/inch). The higher the density, the more durable the fabric. But, what do all these numbers mean, and why do they matter? Up until W.O.L.F.'s class, some of the numbers on fabric hangers were a complete mystery to me. But, after our fabric analysis during day one, we were taught what these numbers mean and why they are important. The numbers you may see on a fabric hanger are:


What you might also find on the hanger, in the shade of indigo used because at the end of the day, indigo is the heart of it all. Since indigo is not water-soluble, it takes a lot of effort to adhere to yarns. A combination of one, 20% (now 40%) dye paste, two, caustic soda to bring the pH level up to make the dye water-soluble, and three, sodium hydrosulphite to reduce the vat and strip oxygen off the indigo molecule is the formula needed for a successful indigo vat. However, we see many advancements eliminating the need for caustic soda and sodium hydrosulfite in modern indigo advancements like aniline free dyes or bioengineered indigo.

The most common indigo dyeing system today is an Indigo Rope Range that has a creel where ball warps are positioned for dyeing, wash boxes where yarn is prepared for dyeing by removing natural oils and waxes in cotton, rinse boxes, dye boxes, skying to allow the indigo to oxidize, steam cans for drying and rollers. With this system, your indigo shade is built with multiple dye dips and skying trips leaving a white core that allows us to achieve the beautiful wear and tear worn denim accumulates or recreate those effects using garment processing.

The final steps W.O.L.F. covered in the class were finishing, washing and testing in denim production, which we will cover on Supply Chain 101, so stay tuned as Simply Suzette collaborates with White Oak Legacy Foundation to build you a comprehensive guide to the denim supply chain, enabling you to make informed decisions whether you are a consumer, fashion student, product developer, or designer.

Check out White Oak Legacy Foundation and follow them on LinkedIn to stay up to date on future events. Until next time friends, always be curious and stay diligent! 🤠