Metal Construction News, February 2021

SPECIAL FEATURE Prepainted metal is available in thousands of different color options To produce a specifi ccolored coating colored pigments are selected and blended together Alexander says Coating manufacturers have a variety of pigments from which to choose and the color selection will determine if organic or inorganic pigments or both are needed In addition to colors there are a variety of visual effects that can be achieved with metal panel coatings Gloss and Sheen Gloss is a unit of measurement that specifi es how much refl ectance a coating will have The way light refl ects off the surface of an object is an indication of its gloss level explains Alexander Similar to interior paints metal coatings are available in various gloss levels from matte lowgloss standard and high gloss The way in which a fi nish refl ects light can be considered part of its aesthetic properties These attributes are naturally considered aesthetic properties of a fi nish explains Blackenship As an organic coating ages it may break down at the chemical microscopic level Depending on the resin system this process may happen at different rates The microscopic chemical breakdown evolves into macroscopic degradation and erosion of the bulk fi nish itself The fi rst indication of this process is a change in gloss Once this process also called photochemical degradation starts it follows an exponential curve The integrity of the fi nish weakens reducing its barrier properties This can result in corrosion formation chalking and color fade It is important to consider gloss as more than an initial number but a property that is indicative of the performance of a coating over its life When it comes to the different types of coatings Moffat explains that polyesters have a wide gloss range while PVDF fl uoropolymers only offer a gloss range of 10 40 degrees and FEVE fl uoropolymers are available with full gloss ranges Low gloss coatings hide metal and paint defects and have always been the preferred level of gloss he says Gloss will change the look of the coating dramatically even with the same base color Micas and Metallics In addition to solid colors coatings with a pearlescent shimmer can offer different visual effects Mica and metallics are a blend of mica and aluminum pigmentation that add varying degrees of sparkle to the surface to produce a metallic luster look explains Alexander Micas and metallics sparkle and add life to the coating adds Moffat Sunlight and angles accentuate the effect They are the most popular commercial coating but the hardest for color control Application variables can change color on micas and metallics based on how these pigments refl ect by orientation in the paint fi lm Color Shifting Effects To achieve color shifting effects coated fl akes are added to the coating formulation that cause a color shift due to light refl ectivity Colorshifting pigmentation works when viewed from different angles or under changing light sources says Alexander There is a wide range of color shift which can be achieved from dramatic red to a green or more subtle a white to a cream As with mica metallics it is well known in the auto industry and becoming more popular in architectural products Prints and Textures Prints are an effect that mimics natural materials Visual Effects Photo courtesy of Sherwin Williams Coil Coatings 18 METAL CONSTRUCTION NEWS February 2021