Jeans can develop ripples or puckering after washing, and it’s usually due to how modern denim is made. Most jeans include stretch materials like elastane, and “Lycra is sensitive to heat.” When exposed to hot water or high dryer temperatures, the stretch fibers can break down, causing the denim to warp and leaving behind permanent ripples.

Washing habits also play a role. Many people clean their jeans too often, which weakens the fabric over time. As fibers wear out, they shrink unevenly, leading to distortion instead of a smooth fit. Overwashing speeds up this process and makes the problem more noticeable.

The washing machine itself adds stress. During a cycle, jeans twist, stretch, and bunch up—especially if the machine is full. As the article explains, “Jeans get twisted, stretched, and contorted,” creating uneven tension in certain areas. This results in waves or puckers rather than uniform shrinkage.

Water absorption is another factor. Denim doesn’t soak evenly, so some areas expand more than others. As the jeans dry, these sections shrink at different rates, causing a distorted look. Overcrowding in the washer or dryer makes it worse, since jeans can dry in twisted shapes that lock in creases.

To prevent this, use cold water and avoid high heat. Air drying works best, or use a low-heat setting and remove jeans while slightly damp. Turning them inside out, using a gentle cycle, and giving them enough space in the machine can help maintain their shape and keep them looking smooth longer.