If your favorite jeans come out of the wash with odd ripples or wavy lines, especially near seams or thighs, you’re not alone. This is a common issue and usually isn’t permanent. Understanding the causes can help you prevent future damage and preserve your denim.

The primary culprit is uneven fabric shrinkage. Denim, often made from cotton, shrinks when exposed to heat and moisture. When areas like seams or reinforced sections shrink more than others—especially after hot washes or high-heat drying—it creates ripples and puckering.

Another cause is manufacturing tension. Jeans are stitched under varying degrees of tension during production. While they may look smooth when new, these uneven stresses can reveal themselves after washing, causing buckling and twisting. This is more common in poorly constructed or budget jeans, but even high-end pairs can be affected.

Stretch denim, which contains elastane or spandex, is also vulnerable. These synthetic fibers behave differently than cotton and may shrink or degrade unevenly over time. This can warp the fabric, especially after repeated washes and drying.

Overloading your washing machine contributes to the problem. When jeans are crammed into a full load, they can twist or get tangled, which distorts their shape. Rough agitation with heavier items like towels makes it worse.

High-heat drying mistakes can lock in damage. Over-drying denim causes fibers to become brittle and fix ripples permanently. Air drying is gentler and helps jeans retain shape.

To prevent rippling, wash jeans in cold water, turn them inside out, use gentle cycles, avoid overloading, and air dry when possible.