Prepainted metal is obtained by painting galvanized steel and aluminium in a continuous production line, with coil coating technique. In coil coating technique, galvanized or aluminum roll is opened in the continuous painting line and firstly, surface cleaning process is applied. The oil and unwanted substances are removed from the surface to be painted. Then, chromating process is applied to the sheet’s surface and a surface suitable for painting is obtained.

Firstly, epoxy primer is applied on both sides of the metal and it the primed metal is then sent to an oven for curing. The insulating layer or its adhesive is adhered to the metal by means of the epoxy primer layer applied to the insulated surface of the metal. And by this way the sandwich panel gets a composite structure. Since there is no epoxy primer layer in the insulated layer of the naked embossed aluminium, insulation layer cannot adhere to the metal very well and it can shear off in time.The colors desired as a final coat are selected from the RAL catalogue. It is painted in RAL color and type, and cured again. Rolls wrapped as painted. With Coil Coating technique, a uniform paint thickness is obtained at every point of the steel surface.Due to the geographical and environmental characteristics of the projects’s location, polyester, PVdF, plastisol, foodsafe or polyurethane paint is used on the epoxy primer. These paints with different technical characteristics common point is to be wet paints. Paint is the most important factor that ensures metal's long lasting. The metals painted with coil coating technique can be processed easily.

Painted surface is not affected during the forming process. Paint types have different warranty periods. These periods vary depending on the environmental, geographic and climatic conditions and use. The endurance of coil coating painted sheets is 6 years for the polyester paints under normal conditions and for PVdf and plastisol paints at locations without air pollution, acidic and heavy metals and away from the sea and for about 15-20 years. In case of continuous maintenance, the expected life can be 20 years and over.