The effectiveness of the new technology was borne out by the results of an extreme test conducted in a laboratory car-wash according to DIN standards, Caza said.
The water used in the test contains a precisely measured concentration of fine particles and is spread over the paintwork by the rotating washing brushes, leaving behind scratches. After 10 wash cycles in the laboratory car-wash -- reproducing the degenerative effect of some 50 to 100 regular car washes -- the nano-painted sheet metal emerged with around 40 per cent greater gloss than samples with conventional clear lacquer.
Not only is Mercedes-Benz the world's first vehicle manufacturer to offer this more scratch-resistant clear lacquer, said Caza, but the nano-particle clearcoat serves as an early indicator of the huge potential of nano-technology for the future, techniques which allow scientists to reach into and alter the atomic structure of materials.
''Indeed, it will also be possible to give materials in other areas of automotive development new properties which allow them to carry out particular functions,'' said Caza.
The paintwork on the latest cars consists of several exceptionally thin layers, with each fulfilling different tasks.
The painting procedure begins with the phosphating process, in which the car body is sealed in an extremely fine but highly effective zinc phosphate coating. This protects the sheet metal from corrosion and at the same time forms a sound basis for the cataphoretic dip priming -- whose primary function is also to provide a shield against corrosion -- which is next to come. Here, the car body is submerged in a tank of water-thinnable paint, which coats every cavity, corner, groove and edge through an electrophoretic reaction. Together, phosphating and cataphoretic dip priming form a layer only some 22 micrometres thick.
The filler comes next, and it is likewise water thinnable and containing only a small quantity of organic solvent. Its job is to absorb the impact of small stones and to even out the metal structure. The paint particles are electrostatically charged by high-speed rotational atomisers, causing them to be pulled towards the body. This process ensures that the layer of filler, which is some 25 micrometres thick, is distributed evenly.
The next layer of paint is the base coat (approx. 15 micrometres thick), which contains not only the customer's choice of color in pigment form but also, if a metallic finish has been ordered, the tiny aluminum flakes which provide the elegant metallic effect. As with the filler, an electrostatic charge increases the effectiveness of the paint application in this process as well. The base coats used by Mercedes-Benz are water-soluble and contain as much as 80 per cent less organic solvent than conventional paint finishes.