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SURFACE 2018

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34 SURFACE PREP 2018 COATINGSPROMAG.COM By omas R. (Randy) Glover, President and Owner of O.T.B. Surface Preparation and Cleanliness Surface Prep W ikipedia defines "cleanliness" as "there is no dirt, no dust, no stains, and no bad smells." Cambridge Academic Content Dictionary's definition states cleanliness is "the habit of keeping yourself or environment free from dirt." e Free Dictionary defines cleanliness as "the condition of being clean and free of contaminants." Surface preparation should involve the best suited method(s) for the application of a correctly selected coating to protect that surface. Cleanliness should definitely be included in the surface preparation mindset. Coating manufacturers state in their Product Data Sheets (PDS) "surface should be free of all dirt, dust, and contaminants." Obviously, they are encouraging contractors to prepare surfaces just as the above stated dictionaries' definitions. But let's be reasonable: Is " free of all " and "no dust or dirt" possible for a contractor to achieve? Steel Specifications and Guides Specifications rarely, if ever, include the method a contractor should use to prepare a surface or how clean a surface should be prior to coating application. at's usually left up to the coating contractor. A coating manufacturer's PDS may state the desired anchor profile but not the method to achieve that profile. Again, it's left up to the contractor, as is surface cleanliness. e Society for Protective Coatings (SSPC) and NACE International have developed joint surface prepara- tion standards to guide the contractor in achieving the proper preparation. SSPC Surface Preparation (SP) 1, SSPC-SP-2, and SSPC-SP-3 include solvent, hand, and tool cleaning. SSPC-SP-3 through -14 and jointly NACE Nos. 1‒6 and 8 include methods of surface preparation. W hat's interesting is that all these standards employ the words "all " and "visible" when referring to removal of dirt, dust, grease, oils, etc. But there is no recommended method for a coatings inspector or a coatings applicator to employ to verify compliance with the required specification's surface preparation standard. Specifications requiring standards used for surfaces prepared by abrasive blasting state surfaces shall be "viewed w ithout magnification" and " free of all visible." Would it be appropriate for an inspector or contractor to use International Organization for Standardization (ISO) standard 8502-3: Preparation of steel substrates before appli- cation of paints and related products-Tests for the assessment of surface cleanliness-Part 3 Assessment of steel surfaces prepared for painting (pressure sensitive tape)? Let's examine the standard. ISO standard 8502-3 utilizes pressure-sensitive tape applied to the surface using either a calibrated spring- loaded roller or pressure from one's thumb. Under Section 6-Procedure, 6.3 states that the test method in which pressure applied to a tape using a thumb is subjective. After tape is removed, the tape is then compared to a chart numbered 1‒5. e chart is utilized for a visual determi- nation of quantity of dust and then particle size, which is determined utilizing a 10X magnifier. It states: "Dust on blast-cleaned surfaces may reduce the adhesion of subsequent applied organic coatings and, by absorbing moisture, may promote the corrosion of the blast-cleaned steel surfaces. Specifications rarely, if ever, include the method a contrac tor should use to prepare a sur face or how clean a sur face should be prior to coating application. That's usually lef t up to the coating contrac tor.

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