creases

Creases are lines or ridges formed by folding, wrinkling, or applying pressure to a surface. They occur in many materials, including fabric, paper, and skin, and may be intentional, as in clothing and art, or incidental, as a result of use or handling.

In textiles, creases arise where fabric is bent or compressed. The tendency to form permanent creases depends on fiber content, weave, and finishing. Natural fibers such as cotton or linen crease more readily and hold pressed lines, while synthetic fibers like polyester are more resistant. Creases can be minimized by selecting wrinkle-resistant fabrics, using proper laundering and drying methods, and applying heat and moisture to set preferred creases. Ironing and steaming are common methods to alter crease patterns.

In paper and art, creases are deliberate folds that change the geometry of a sheet. Scoring or pre-creasing guides are used in origami and packaging design to produce precise shapes.

In biology, creases refer to natural lines on the skin or joints, formed by repeated movement or aging. Palmar and plantar creases are characteristic of healthy development; skin creases may deepen into wrinkles with sun exposure and loss of elasticity.

In manufacturing, creases can indicate improper handling of sheets and fabrics, but controlled creasing is used to create fold lines in packaging and metal forming.