Why Denimheads Are Waiting for “Train Tracks”

“Train Tracks” are one of the most celebrated details among raw denim enthusiasts pursuing natural fading. This term refers to two parallel, vertical fade lines that form along the edge of the jeans’ outseam (the outer leg seam). Caused by the friction and loss of indigo dye over long-term wear and washing, they resemble the ties of a railway track, hence the name. In the raw denim community, the goal is to cultivate unique “traces of time.” Train tracks have thus become one of the most recognizable details in natural fading.

1. How Do Train Tracks Form?

To achieve this type of fading, the outseam must first have a “raised” structure, which requires sufficient thickness at the seam.

Selvedge: Narrow-width denim woven on old-fashioned shuttle looms features a tight “self-finished” edge that is naturally thicker than the rest of the fabric.

Open Seam with Overlock: For non-selvedge jeans, if the raw edges of the two fabric panels are folded twice separately before being sewn together and pressed open, two raised ridges of thickness will form inside.

Once this raised structure is in place, wear and washing will bring it out. The thickened edge on the inner side of the leg continuously rubs against the fabric surface, while the outseam itself experiences relatively less stress and tension. This causes the dye in this area to fade more slowly, but once the pattern emerges, the contrast is striking. Additionally, as raw denim shrinks, the thickened edge of the outseam shrinks at a different rate than the surrounding fabric, making the originally flat ridge more three-dimensional. This is why many enthusiasts say, “Just wash them inside out often, and the ‘train tracks’ will appear naturally.”

2. How to Cultivate Beautiful Train Tracks?

Forming train tracks requires patience, as the outseam is not prone to abrasion, making significant fading difficult. However, with the right approach, you can accelerate the process.

1. Pay attention to the seam finish. Prioritize raw selvedge denim, as the inherently thick fabric edge makes it easiest to form high-contrast train tracks. For non-selvedge pants, choose styles with an open seam construction on the inside of the outseam.
2. Opt for cotton thread stitching. Cotton thread shrinks during washing, further pulling and accentuating the three-dimensional quality of the outseam, creating more vivid marks.
3. Before wearing, press the outseam flat with your hands or an iron. This creates a wider, flatter “track,” laying the foundation for clear, parallel fade lines. During wear, engage in activities like squatting and walking to increase friction along the outseam edges.
4. Wash inside out and dry inside out. This reduces overall indigo loss, intensifying the fade contrast, and helps set the raised structure on the inner leg during the drying process.

3. Achieving Train Tracks Through Industrial Washing

Beyond natural fading, professional industrial washing techniques can precisely “replicate” the train track effect through processes like creasing, PP spraying, and stone/enzyme washing. Pants stitched with cotton thread have a strong texture and pronounced relief, resulting in equally eye-catching train tracks. This washed-and-distressed approach allows for jeans with beautiful train tracks to be produced without waiting through a lengthy breaking-in period. Our #9318 Blue features train track effects replicated through industrial washing.