Ironing is the use of a heated tool (an iron

Iron (appliance)

A clothes iron, also referred to as simply an iron, is a small appliance used in ironing to remove wrinkles from fabric.Ironing works by loosening the ties between the long chains of molecules that exist in polymer fiber materials. With the heat and the weight of the ironing plate, the fibers are...

) to remove wrinkle

Wrinkle

A wrinkle is a fold, ridge or crease in the skin. Skin wrinkles typically appear as a result of aging processes such as glycation or, temporarily, as the result of prolonged immersion in water. Wrinkling in the skin is caused by habitual facial expressions, aging, sun damage, smoking, poor...

s from fabric. The heating is commonly done to a temperature of 180-220 °Celsius, depending on the fabric. Ironing works by loosening the bonds between the long-chain polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

s in the fibers of the material. While the molecules are hot, the fibers are straightened by the weight of the iron, and they hold their new shape as they cool. Some fabrics, such as cotton, require the addition of water to loosen the intermolecular bonds.