Part 2 of 2 of this series on Denim Construction terms.

If you missed Pt. 1, you can click over to it here. Otherwise, let’s jump right in.

illustration of warp and weft threads

Warp and Weft
These are the threads that make a weave. The lengthwise warp yarns are held stationary with tension on the loom while the weft is drawn through over and under the warp by hand, shuttle, or projectile. In denim, the weft yarns are usually left white and the warp are the forward facing dyed yarns. If you like dark, deeper color - look for double indigo jeans where both the warp and weft have been dyed like the IDHT Double Indigo from Tanuki.

Dip Dyed vs. Rope Dyed
Most denim is dip dyed. Warp yarns are dipped in indigo, left to oxidize, repeat. The more times it’s dipped, the darker it gets.

Rope Dyeing is a more thoughtful approach to future fading. Instead of just tossing them into the dye, the warp yarns are twisted into a rope and quickly dipped into the indigo baths again and again until it reaches the desired hue depth. This creates a ring dyed yarn that fades better and faster than fully dyed yarns. It has a bit more character to it, but with both processes the core remains white and will become the indigo rainbow that everyone loves.

detail image of slubby denim
detail image of neppy denim

Left: Texture of Slubby denim. Right: Neppy Denim's Snowy quality

Slub and Nep
They’re different, but both results equal texture. When a garment is ‘neppy’ or has ‘neps,’ it means that the garment has been woven in a way to allow some of the cotton fibers to extend and protrude from the surface. This produces a snowy effect with fading that is both horizontal and vertical and the neppy fibers become further pronounced. Creating neppy cotton fabrics is accomplished by allowing knots and broken fibers to occur when the yarn is spun. Low tension on the loom furthers the process by agitating the fibers and leaving them more exposed through additional shaking and tangling throughout the weave.

The slub refers to warp yarn that varies in thickness throughout the garment. The result is a fabric without uniform texture. To make it even more textured, the tension is set low so that it shakes a little as it weaves. What you get is a rougher handfeel and fades that run more vertically (remember that the warp yarns are the stationary ones that run up and down).

orslow 105 and 107 denim jeans

Sanforized vs. Unsanforized
Sanforized is preshrinking garments by a controlled compressive process. Sanforization limits further shrinkage of the fabric to less than 1%. Fabric that doesn’t go through the sanforization process is likely to shrink up to 10% on the initial wash and continue to shrink some until the third wash. During the process, uncut fabric is fed into a sanforizing machine and moistened with water or steam to promote shrinkage. The fabric is then stretched through a series of rubber belts and cylinders before being compacted to its final size.

Unsanforized doesn’t really mean anything. It’s a word invented to point out that the garment wasn’t sanforized because that wasn’t otherwise already pointed out. Other synonyms to the word "unsanforized" that you’ll notice are “shrink-to-fit” and “loomstate.”

So the question is, what do you want out of the garment? Do you want it to fit perfectly right away, but not last as long? Or, do you prefer to do the work yourself and have a bit of an uncomfortable phase? If you prefer the latter, remember that unsanforized means that it hasn’t been pre-shrunk and should be purchased at one to two sizes above your typical sizing.

detail image of single needle stitching
detail image of chain stitching on jeans
detail image of lockstitch on denim jeans

Left to Right: Single Needle Stitching, Chainstitch, Lockstitch

Single Needle Stitching
is a lockstitch that uses two threads that reinforce each other by entwining the upper and lower threads. Single needle stitching allows for a smoother seam but must be done on a hand-governed machine at low speed and requires a steady hand with metronome-like pacing. For many seams, it doesn’t get better than this, but because of its difficulty, is only used by the select masters behind no-cheat machines. Stevenson Overall Co. is one of the few that uses it.

Chainstitch vs. Lockstitch
The chainstitch is the original way to hem, but it can also be sometimes spotted on other seams. Only special, vintage machines like the Union Special can do it. Although the chainstitch looks better and produces nicer fading (due to how it slightly bunches the denim), it tends to unravel. It’s been mostly replaced by the lockstitch.

A lockstitch uses a bobbin shuttle to tie up the thread as it passes through the fabric and locks it into place. It’s stronger than the chainstitch, but it doesn’t look as clean if you cuff.

Many premium denim brands today use the chainstitch. It’s one of the many details that add up to why modern denim is better than it ever has been - an attention to aesthetic detail that honors blue jean traditions.

Although the story of their construction has interesting depth, it’s the personal odyssey of a good pair of jeans - the fades and tears, honeycombs and whiskers - that reminisce. Knowing what to look for is just the beginning...