Hydrophobic treatments ensure that water runs off surfaces fast and prevent capillary suction. In this way the rain can wash off larger particles. Although not one hydrophobic agent can be used for all materials, most agents are silicon-based agents like silane and siloxane. Fluorine-containing polymers are alternatives to the traditional treatments; the theoretical possibilities for creating hydrophobic and nonstick surfaces that will prevent soiling are better for these substances. Experiments performed on commercially available roofing tiles with a hydrophobic treatment could not confirm this. X-ray Photoelectron Spectroscopy analysis revealed that a fluorine-containing agent was used, a hydrophobic effect was visible at the surface but the water uptake in the tiles were up to 10 times higher than in ordinary tiles. After a year of exposure biological growth was detected at the treated tiles as well as on ordinary tiles, the growth was more visible at the untreated tiles.
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