It consists of a coating or several layers of coatings which are released from a carrier film and deposited on a substrate.
The process of manufacture:
The carrier is a thin film (0.0125-0.025 mm) of cellulose acetate or polyester film.
First coat: Film is coated on one side with a release agent (usually wax) which melts on application of heat to the uncoated side of the carrier film.
Second coat: The carrier is passed through a colour or metallic coating process.
Third coat: Heat activated sizing to obtain acceptable adhesion is applied as third coat. The sizing is formulated to bond on the particular material that is decorated.
Fourth coat: When extreme abrasion and solvent resistance is required a protective coat between the release coat and the colour coat is applied. Dye is added usually to the protective coat. These protective coats are developed to protect the roll leaf from alcohol, salt spray, detergents etc.
Creativity: simulated wood grain roll leaf is used for wood graining radio/TV cabinets. In some wood grains 5 coats are applied:
1st coat is the release coat, 2nd is protective top coat, 3rd coat is the grain which is applied by a textured roller which is engraved to simulate the particular grain desired, 4th coat is the base coating which is a solid pigment colour to complete the two tone effect and the 5th coat is the size coating. Wood grain roll leaf is available with a gloss (lacquered) finish or with a hand rubbed finish. For hand rubbed finish an etched polyester carrier strip is used.
The roll leafs release at temperature from 2500-3500 F. But the foils releasing at lower temperature will lower the die heat and thus will reduce distortion of parts with thin walls. It will also lengthen the life of silastic dies and the soft metal dies.