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SurfaceTechnology GERMANY, 05 - 07 June 2018
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Putting color to the metal

Colored metal surfaces are increasingly popular in architecture and interior design. They are also on the agenda at O&S 2016 in Stuttgart.

08 Dec. 2015
Ringe Beschichtung

One of the companies presenting innovative solutions at O&S is Munich-based Poligrat, which has developed a new technique based on a vitreous ceramic coating. As an all-embracing event, O&S covers the entire spectrum of surface technology, presenting coating methods for metals, plastics, glass and ceramics. Among the most prominent topics addressed are electrolytic coating technology, industrial plasma surface treatment and micro-materials processing.

Many current methods for producing colored metal surfaces, including PVD coating and chemical dyes, do not meet increasingly stringent and complex environmental and customer requirements. Surfaces produced with these methods often do not have the desired properties – e.g. color palette, depth or intensity – as needed for versatile use. Poligrat has developed an entirely new technique based on a vitreous ceramic coating to address these issues. The Verospectral® coating preserves the specific metallic character of the surface while at the same time optimizing usability. "With Verospectral we've created a product that can simultaneously meet demands for aesthetic diversity, a wide range of applications, cost effectiveness, durability, resource conservation and environmental protection," said Siegfried Pießlinger-Schweiger, owner and CEO of Poligrat.

Verospectral – the name means "true color" – consists of a transparent, colorless vitreous ceramic coating just two to four microns thick. The coating contains inorganic pigments in direct contact with the metal, arranged in a defined pattern and concentration to generate specific light and color effects. The tiny pigment particles are evenly distributed over the surface, preserving the metallic character by leaving the metal surface visible between the individual particles. Color saturation can be adjusted by varying the number of particles per unit area. A nearly seamless range of colors can be achieved with the coating, including black, white, and intermediate gray tones. In addition, the depth and intensity of the individual hues can be adjusted from a slight haze to full coverage. Multicolor surfaces can also be produced. The colors change with the viewing angle and the angle of the incident light, giving the surface a livelier aspect.

Coating stainless steel, aluminum and zinc
Starting from eight basic colors, virtually all desired colors and tints can be produced by mixing the pigments appropriately. The pigments are first pulverized to particle sizes significantly less than one micron using a method developed by Poligrat. They are completely covered by the coating, and thus not exposed to the ambient environment. Only the vitreous ceramic coating is in contact with the environment, and it alone determines the surface's properties in use. The interplay of colors and shapes creates fascinating potential for highly diverse implementation of architectural components. Metallic surfaces can be fashioned in particular with stainless steel and Corten steel (a weatherproof structural steel), aluminum and zinc. Application is largely independent of material quality and finish.

Poligrat is exhibiting Verospectral, which has already been honored with a special mention in the Architecture + Construction 2015 Innovation Award competition, within its company showcase at O&S 2016.

Initial projects for colored metal surfaces
Poligrat currently has several projects for the new coating in the pipeline, and noteworthy reference projects for their Poliant® coating are already underway. Poliant is a vitreous ceramic coating like Verospectral, but without the color. In a project started in 2013, the mezzanine floor of the Marienplatz metro station in Munich is being completely renovated and redesigned. Poligrat is a major contributor to the new wall covering. The stainless steel facade has a Poliant coating for graffiti and fingerprint resistance and easy cleaning, which in comparable applications has yielded cost savings of up to 70 percent for property owners and operators. The coating also increases corrosion resistance and complies with all building inspection approval requirements as well as fire protection standards. Coated stainless steel panels are also used in the Olympiazentrum metro station in Munich.

"An important aspect of Verospectral is its durability. Our coating is resistant to aging, UV radiation, dirt and pollution, temperatures up to 400°C, and most chemicals," explained Pießlinger-Schweiger. Furthermore, no environmentally harmful substances are used in its production, it contains no chromates, and there is no accrued waste. The actual production process is simple. Verospectral is applied by spraying and then baked. Interested persons can find out more from Poligrat at O&S 2016.

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