the painting process
Whatever its pigment, paint today is always applied in the same way and comprises a filler-based totalcoating system with a two-component clear coat. Unless ‘wraps’ are involved, painting is normally a three-stage process. The first stage is a primer designed to create a uniform base. Primer is now thinner than in the past thanks to advances in sheetmetal stamping, which has resulted in smoother surfaces. Primer thickness is usually 8 to 38 microns (thousandths of an inch).
As the name suggests, base colour gives the body its colour. This too is thinner than before, and the thickness applied varies, like primer, between 8 and 38 microns. The top layer is clear-coat lacquer. Invisible as such, its role is to protect the base colour from oxidation by atmospheric impurities or degradation from ultraviolet light.
The application process is critical if the finished quality is to be maintained through the life of the body. Low paint density occurs if the base coat is not allowed sufficient hardening: Porsche’s new system is particularly rigorous in the length and temperature of its drying schedules.
Modern water-based paint pigment is not especially hard. On Mohs scale of mineral hardness, where talc is 1H, glass is 6H and diamond 10H, paint is only slightly hard at 2H. Within this range OEMS vary in their choice of paint hardness. Mercedes and Volkswagen use harder varieties; Porsche paint is usually medium hard.