creasing

Creasing is the formation of a crease, a sharp, elongated bend or fold that introduces a line of plastic deformation in a material. It can be intentional or incidental, temporary or permanent.

In textiles and clothing, creases are used to give shape and improve drape. Garments are pressed to set creases, or fabrics are finished with crease-resistant treatments. Over-creasing can cause permanent set or fabric damage, while some fabrics are designed to hold creases for a tailored look.

In paper and cardboard, creases are created by scoring or folding to guide future folds. This is essential in packaging, bookbinding, and greetings cards, where pre-creased lines allow precise, repeatable folds and easier assembly.

In origami and geometric contexts, a crease is a line along which a sheet is folded. The pattern of creases, called a crease pattern, determines the final form; folds are classified as valley or mountain, depending on the direction of the bend.

In engineering and manufacturing, creases in metal sheets or composites can be intentional stiffeners produced by bending, or unintended defects from compressive stress. The presence and angle of a crease affect strength, formability, and risk of failure, making crease control important in design and quality assurance.