CoatingsPro Magazine Supplements

STEEL 2019

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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Page 4 of 27

COATINGSPRO STEEL SURFACES 2019 5 Steel Substrates and Surface Prep: What to Know Before You Coat Exterior coating restoration of architectural steel surfaces requires proper preparation and high-performance products to ensure optimum protection. From environmen- tal conditions, to the type of steel and its condition, to the coating system formulation, several details can affect the short- and long-term success of recoating a steel exterior. The 4 "Cs": Climate, Corrosivity, Cleanliness and Coating System Sunlight, moisture, temperature extremes, wind, chemi- cal pollutants and abrasion can break down coatings over time. Chemical agents and free radicals in sunlight, water and atmospheric pollution can react with a coating's chemis- try, attacking the bonds of the coating's binder resin. W hen coatings erode and expose the steel substrate, these climate conditions cause electrochemical corrosion. Contractors should therefore pay close attention to the structure's "micro-climate," including moisture, humidity and UV exposure when specifying high-performance coating systems. Analyzing the steel's existing condition will help determine needed surface cleaning, preparation processes, and additional chemical or coating treatments for a multi-coat system. Following ISO or NACE standards to identify surface condi- tions, atmospheric corrosivity category, level of cleanliness and suitable surface profile will help ensure coating longevity. Consult the Coating Manufacturer Coating systems are formulated to work with specific substrates. A formulation developed for masonry is not suited for steel surfaces. Coatings manufacturers provide detailed informa- tion about substrate/coating compatibility on their product data sheets, field application guides, and specifications. ese documents also provide information on coverage, VOCs, dry rate, viscosity, substrate preparation, and proper application. e condition of the existing coating system and substrate will indicate whether complete removal or overcoat- ing is the best solution. e amount of corrosion or degra- dation present, degree of coating defects, number of coats and adhesion strength between coats are factors to consider before making an overcoat or complete removal decision. e coating manufacturer can make a case-by-case assess- ment and determine the optimum solution. With their assis- tance, you can also verify that the specification for a project complies with the warranty. A primer provides an important bonding layer to help the topcoat adhere to the surface. Manufacturers recommend install- ing a mock up, with proper surface preparation, and then testing one or multiple primers using ASTM D3359 Standard Test Method for Measuring Adhesion by Tape Test before coating. Inadequate adhesion will cause the coating to fail, eliminat- ing its protective properties. Sometimes inter-coat adhesion, or compatibility between primer and topcoat, is overlooked but can be an issue if not considered. Manufacturers extensively test their formu- lations for performance and compatibility, so it is wise to source a multi-coat system from the same manufacturer. Benefits of PVDF-Based Coatings To coat steel surfaces, many specifiers are turning to single-component, water-based coating systems such as NeverFade® Façade Restoration Coatings with Kynar Aquatec®. Formulated with poly vinylidene fluoride (PVDF), a tough engineering thermoplastic that withstands thermal, chemical and ultraviolet conditions, the low VOC coating system has 18+ years of proven weatherability in extreme conditions. It promotes long-term protection to steel surfaces against corrosion, UV degradation, color fading, mildew growth, dirt pick-up and abrasion. APV Engineered Coatings (800) 772-3452 Company Profile: APV Engineered Coatings SPONSORED CONTENT

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