A decal (/ˈdiːkæl/, /dɨˈkæl/, or /ˈdɛkəl/) or transfer is a plastic, cloth, paper or ceramic substrate that has printed on it a pattern or image that can be moved to another surface upon contact, usually with the aid of heat or water. The word is short for decalcomania. The word decalcomania is derived from the French word decalquer, and was coined by Simon François Ravenet about 1750; it became widespread during the decal craze of the late 19th century.
Decal is composed of the following layers from top to bottom:
- A paper or film face-stock makes up the top layer of the labelstock. The printing is done on the upper side of the facestock.
- An adhesive layer is applied to the bottom of the face stock.
- A silicone or release coating layer is applied to the upper side of the backing material.
- A paper or film liner provides the bottom layer of the labelstock.
Different variations of decals include: water-slide or water-dip; and vinyl peel-and-stick. A water-slide (or water-dip) decal is screen-printed on a layer of water-soluble adhesive on a water-resistant paper, that must first be dipped in water prior to its application. Upon contact with water, the glue is loosened and the decal can be removed from its backing; overly long exposure, however, dissolves the glue completely causing the decal to fail to adhere. A peel-and-stick decal is actually not a decal as described above, but a vinyl sticker with adhesive backing, that can be transferred by peeling off its base. The sign industry calls these peel-and-stick vinyl stickers vinyl-cut-decals.
Decals are commonly used on hot rod automobiles and plastic models. They are also used on guitars as a way of personalizing them.
Government agencies of all types also use decals on vehicles for identification. These decals are referred to as fleet markings and are required by law on all fire and law enforcement vehicles in the US. Most fleet markings are created from reflective vinyl with an adhesive backing that is applied in a peel-and-stick manner. Vinyl comes in large rolls that are fed through a plotter (cutter) or large-format printer/cutter. The designs are created in specialized computer software and sent to the machines via cable link for production. Once the design is cut into the vinyl, the excess vinyl on the sheet is removed in a process called weeding. Finally, a paper pre-mask is applied to the top of the vinyl design to allow easy application of multiple letters and shapes at one time.