There can be several reasons why it is necessary to change the surface properties of metals. One is that high-quality products should also look high quality. Design-oriented screws can contribute to this aim with surface technology making it possible. These following main methods of decorative surface treatment are possible:

Chemical blackening: The screws are immersed in an acidic or alkaline solution during this process, which is also known as blackening. This forms a decorative black layer known as a patina.

Electro-polishing: The screws are furnished shiny surfaces in this surface technology. For this purpose, a thin layer of material is removed using electrochemical means. Chemical treatment (passivation) furnishes the screw with a layer that protects it from oxidation. Owing to the hygienic and smooth surfaces it provides, this surface technology is used by companies in the pharmaceutical and food industry.

Pickling and passivation: During pickling, the screws are dipped into an acid bath to clean off greases, oils and dirt. The treatment in the passivation bath allows the protective layer (passive layer) on the stainless steel to form faster again and thus protect the screws against environmental influences.