CoatingsPro Magazine

MAR 2017

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 58 of 84

58 MARCH 2017 COATINGSPROMAG.COM Exam Time Over the course of the 24-day project, a crew ranging in size from two to seven men worked on the rooftop of the Christian Missionary A lliance Sun Kei Primary School. Since the polyurea waterproofing system was to be applied directly on top of the preexisting roofing membrane, the crew did not have to engage in the costly, time-consuming, and environmentally unfriendly effort of tearing off the building's roof. at being said, the first step in the process was to clean the roof of debris, contami- nants, and any loose existing roofing material. T he HK P team used a blower, vacuum, and a 3,000 - psi (20.7 MPa) pressure washer to clean the substrate. T he entire area was prepared prior to the application of the coating materials. With the roof area clean, it was time for the crew to apply the primer layer. According to Wong, Pentens E-500SE is a unique state-of-the-art, two-component, ambient-cure, self-emulsified hydrophilic yet organic, solvent-soluble epoxy resin. e E-500SE is resistant to humidity and has excellent dry and wet adhesion. e crew applied the E-500SE at an average thickness of 0.3 mm (11.8 mils). e next step in the process was for the HKP team to apply the sealer layer. "e crew used a metal trowel and scraper to apply the sealer at a thickness of 0.5 mm [19.7 mils] to the entire roof area. Pentens E-501S is a high-strength, excellent adhesion, ready-to-use, solvent-free, two-part epoxy putty filler. It is environmentally friendly with low volatile organic compounds [VOCs]," stated Wong. e E-501S is liquid- and chemical-resistant and can be applied to slightly damp surfaces — a huge advantage for this particular job considering the extreme ambient humidity. For the waterproofing part of the coating system, the HKP crew applied Pentens SPU 1000, which is a solvent-free, two-component pure polyurea spray coating. According to Pentens, the seamless coating provides an elastic and tear-resis- tant surface for applications subjected to extreme wear and tear, strong impact, and chemical exposure. e team applied the polyurea material at an average thickness of 2.0 mm (78.7 mils) using a Graco Reactor 2/E-XP2. At this point, it was time for the application of the topcoat. Two coats of Pentens NPU-12 were installed using an airless sprayer. "Each layer was applied at a thickness of 0.1 mm [3.9 mils]. Pentens NPU-12 is a nanotechnology polyurethane coating that is durable, water-repellent, and fungus/algae/ bacteria-resistant, as well as UV [ultraviolet]-resistant and scratch-resistant. It has an anti-corrosive finish for a wide variety of exterior and interior surfaces," explained Wong. e crew applied this layer, in a vibrant purple hue, to a total average thickness of 0.2 mm (7.9 mils). " T he school chose the pur ple color because they wanted the color of the roof to match the whole building design. A lso, the school is located in Choi Hung Estate near Choi Hung subway station. Choi Hung in Cantonese means 'rainbow,'" explained Wong. "A" for Safety roughout the duration of the project, Wong and the HKP crew paid close attention to all aspects of jobsite safety. "e roof is surrounded by parapets and an anti-climb high security wire fence, so fall protection measures weren't necessary. However, applicators wore personal protective equipment [PPE] at all times, especially when applying the polyurea coating. e crew's PPE included safety helmets, DuPont/Ty vek suits, 3M 6000 series half-face mask respirators, anti-slip safety boots, and MAPA professional gloves," said Wong. No "points" taken off for this part of the job! Final Grade Once the coating system was completed, the HKP team had time to reflect on the successes and challenges that they faced onsite. "Beyond the hot and humid weather, the project went very smoothly, a fact that I attribute to a skilled and efficient crew Over the course of the project, the crew wore proper safety gear. That included safety helmets, Ty vek suits, 3M 6000 Series half-face mask respirators, anti-slip safety boots, and MAPA professional gloves, when necessar y. Concrete Roof Recoat The crew applied Pentens SPU-1000 polyurea at an average of 2.0 mm (78.7 mils), followed by two coats of Pentens NPU-12 polyurethane nano coating at an average of 0.1 mm (3.9 mils) each.

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