CoatingsPro Magazine

MAR 2015

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 30 of 90

30 MARCH 2015 COATINGSPROMAG.COM The metals we are protecting with field-applied coatings are mostly steel, occasionally aluminum, and they most often occur at the building entrance and entrance canopy at street level. Specifying Success for the specifer and the painter on the type and scale of jobs we work on? Polyaspartic Coatings Several diferent coatings manufacturers ofer a product using the polyaspartic chemistry; these are two-component, high solids, and high gloss coatings. Most of these products seem to have volatile organic compound (VOC) levels of 250 g/L or lower, which comply with LEED 2009 IEQC 4.2 for interior anti-cor- rosive/anti-rust paint. For exterior work and for this type of coating, this level of VOCs is acceptable in most locations. Surface preparation for polyaspar- tic coatings depends on the end service environment. Tese coatings appear to be similar to "traditional urethanes" except for variable but relatively short open times. From looking at the liter- ature, most are marketed as DTM products to the original equipment manufacturer (OEM) market where short open times would be an advantage. Tese products can also be applied over the zinc-rich primers as specifed in our tried-and-true assembly. As a represen- tative said, "Tese are incredibly similar to polyurethanes. Tey are two-part systems, and the most common appli- cation method is spray, with brush and roll typically for touchup or small areas. With most polyaspartics being 65–70 percent solids by volume and specifed in the 6–9 mil [152–229 microns] DFT [dry flm thickness] range, it becomes just about impossible to roll that much wet coating in one application. From most of my experiences with demos and such, painters like the product; it applies very similar to the polyurethane but won't run and sag." In addition to being used in the OEM market, I am told they're also being used in the protective coatings market and on bridges and highways for new and feld maintenance work. With proper preparation, the paint's quick fnish does not seem to be an insur- mountable issue. Any fnish coat simply has to be protected from further work at the construction site. One major concern mentioned by contractors was that, with any new coating, availability is a must — availability from national manufacturers and availability in quantities needed for large and small jobs, including one more gallon (4 L) of the custom color needed to repair feld-damaged, fnished work. Tese products can be a great addition to our specifcations, and enough diferent manufacturers have them to provide good availability and competition. Te short open and recoat times, though, will discourage the use of these products where the fnish has to be revisited for whatever reason. Fluoropolymer Coatings It seems that in architecture, we either want one material to contrast with its neighbor or to blend in seamlessly. When trying to achieve the latter, I have on many occasions had to tell the architect why the polyvinylidene fuoride (PVDF) painted louvers will not look exactly the same as the PVDF painted wall panels when both are using the same color from the same paint manufacturer, especially when the paint color is a metallic! So it is with some fear and dread that I entertain the possibility of adding feld-coated structural steel to the list of PVDF (or at least fuoropoly- mer) coated products on the job. PVDFs and other fuoropolymers as coating resins have been with us since at least the late 1960s. Tere are many fuoropolymer paints on the market using resins from many well-known manufacturers, and the application methods range from powder-coating and more traditional solvent-borne products using high heat curing to ambient temperature curing products for feld application. Tese have proven to be coatings of positive weathering capabilities, including very high color and gloss retention, low buildup of dirt, and high mildew resistance. Te option for air-dried fuoro- polymer coatings was developed in the mid-1990s. Field application of these air-dried products followed shortly thereafter, and they are used by specialists in building restoration and refnishing regularly. A round 2010, a PV DF water- borne latex, introduced for the development of coatings for metal and other substrates that can be cured at ambient temperatures, further expanded the use of f luoropoly mers. In a market looking for low VOC products, this is an added bonus. Another advantage of fuoropolymer resin-based coatings is that factory-ap- plied coatings can match any feld-coated material or touch up completed with a color-matched latex-based coating. In addition to the color matching advantage, we can be confdent that this feld-ap- plied coating will weather the same as the factory-applied coating. Various coatings companies are developing formulations or promoting water-borne PVDF coatings under their own brands for various substrates. But what about my structural steel? Te answer seems to be probably, and most probably for the steel exterior doors that I want to match (I use the term "match " under advisement) the curtain wall or metal wall panels. Specification Suggestions Both the polyaspartic and fuoropoly- mer resins have great potential. Te polyaspartic resin has the ability

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