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Knowing Your Raw Denim: Slub and Nep - Meermin

Knowing Your Raw Denim: Slub and Nep - Meermin

David Shuck
December 09, 2025

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Knowing Your Raw Denim: Slub and Nep

Our comprehensive guide to slub and nep, two often mentioned but lesser known facets of a pair of raw denim.

James Smith

When it comes to the realm of raw denim, two of the most pertinent, yet often misunderstood, characteristics are nep and slub. Though these terms may seem like silly, redundant jargon, we can’t stress the importance of these denim traits. Not only do they affect the feel and texture of raw jeans, but they also impact the overall fade and evolution of any pair of denim.

What is Slubby Denim?

Close-up of some slubby denim by Samurai. Image via Redcast Heritage

Slub refers to fabric made with a warp yarn that differs in thickness throughout the weave. This results in denim with an uneven, sometimes rough texture, which will have a much different hand than denim woven with uniform yarns.

In some slubby denim, a technique called loom chatter is employed during the weaving process to help make the texture of the finished fabric even more irregular. The layman’s explanation of loom chatter is that the shuttle looms used to weave the fabric are set to a lower tension level while they weave the yarns. This lower tension setting makes the looms literally shake while they weave the denim, an action which, in addition to the naturally uneven nature of the yarn used to weave the denim, makes the product even more uneven and textured.

Slubby denim can either possess a softer or rougher feel than most raw denim, depending on the cotton used. Aside from the difference in texture that slubby denim is noted for, its irregularity in yarn thickness also tends to result in more interesting fades.

Specifically, these fades tend to run more vertically along the fabric, rather than horizontally. The reason behind the unusual fading characteristics in slub denim is very interesting, as the vertical fading occurs because the indigo dyes tend to fade at different rates based on the varying thickness of the yarn used to produce the denim. This vertical fading characteristic is also known as Tate-Ochi, or “vertical falls”, in Japanese.

Faded slubby selvedge denim from Hanzo ‘The Raid’ Jeans. Notice the unique waterfall texture caused by the slubby weave of the denim, which has emerged as the denim has faded.

/ In Partnership with Meermin /

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What is Neppy Denim?

An extreme example of Nep via Naked & Famous.

Nep is often confused with slub because it also refers to a non-uniform texture. However, the difference between the two often needs to be very clearly defined. When a garment is neppy, or has nep, it usually means that the fabric of the garment has been woven in a way that some of the cotton fibers extend and protrude from the main surface. If these fabrics have a contrasting weft yarn, they tend to possess a “snowy” look, as if freshly fallen snow is sitting on the surface of the denim

Have you ever stumbled upon a pair of jeans that seemed to have little particles of white fluff protruding from the main part of the garment? It may have looked a little bit like the images above or below.

Close-up on horizontal and vertical nep fades..

Snowy Nep Whiskers

Loom chatter also plays a role in the production of neppy denim. As noted, neppy denim usually has visible fibers exposed from the main surface of the fabric, which are usually knots and broken fibers within the yarns that occur as they are spun and then woven. Loom chatter exacerbates the nepping process by further agitating the fibers and leaving them more exposed through the shaking and tangling of the yarn while the loom weaves.

ONI Crushed Concrete Selvedge (olive weft) via Redcast Heritage.

Some artisan denim makers use denim that is both slubby and neppy. Japan’s ONI Denim is known for this, with their ‘Crushed Concrete’ series being their slubbiest and neppiest raw selvedge denim offerings (see image above). Pure Blue Japan also produces denim that combines slub and nep.