Especially in large conurbations, the high levels of carbon black and dust pollution rapidly lead to soiled building frontages and high renovation costs. Developed by BASF in Germany, COL.9 based coatings provide that the colour tone of buildings remains stable and there is no surface chalking even after years of exposure to weather. While COL.9 shares the properties of hardness and low dirt pick-up with silicate coatings, its flexible, organic content implies that it does not have their major drawback - their susceptibility to cracking, which can rapidly lead to the entire coating flake off.
The facade withstands the influence of weathering with the help of nanocomposit coatings.
A development period of almost ten years was required to progress COL.9 to market. The biggest challenge was to combine the mineral nanoparticles homogeneously and inseparably with the organic dispersion to produce composite particles. The mineral particles provide the coating with a hydrophilic, i.e. water attracting surface on which raindrops are immediately dispersed.
As regards cleanliness, this offers a dual benefit: in heavy rain, particles of dirt are washed off extensively from the facade surface. Also, the thin film of water remaining when the rain has stopped dries extremely quickly, which prevents mold formation.
After several years spent passing through BASF's development laboratories, the first COL.9-based facade coating is now on the market: Herbol-Symbiotec® from Akzo Nobel.