Products Finishing

NOV 2013

Products Finishing magazine is the No. 1 industrial finishing publication in the world. We keep our readers informed about the latest news and trends in plating, painting, powder coating, anodizing, electrocoating, parts cleaning, and pretreatment.

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Page 39 of 59

CLINIC PAINTING Inspecting Paint Texture Q. The following question/answer was posted back in 2003. Is the answer you provided then still valid today? Are paint texture standards still not available? I'm facing the same problem with my suppliers and my incoming inspection. For my supplier, it is sufficient that I specify "smooth paint texture" in a metal case assembly drawing, however my incoming inspection rightly complains that "smooth" is not a measurable characteristic and therefore it cannot be inspected for compliance. Q. We do not paint our products in-house. Instead, we rely on outside suppliers to apply paint finishes. My company has used the "it looks good to me" inspection process for painted parts for the past 30 years. I have found that the temperament of the inspectors has a great deal to do with what is accepted and what is rejected. My suppliers have asked for a set of standardized painted inspection chips that would show them what is acceptable and what is not. These chips/plates would be representative of a paint finish that is an acceptable industry standard. I believe something visual, like paint inspection chips, would allow the supplier and our inspectors to check the paint finish to the same standard. Our most common reject is for texture, which is always identified as orange peel. The supplier says it's texture and minimal in appearance; we say it's orange peel. Is there someone who sells paint chips that are used for this purpose? Any help you can provide will be greatly appreciated. —M.M. A. Relax, M.M. If it's any consolation to you, yours is not the only company using the "it looks good to me" inspection process. Unfortunately, the inspector's temperament can influence what is accepted and rejected. You are going in the right direction, having textured paint chips made to be used as standards. Not only will they provide guidelines for your suppliers, they will also remove the temperament factor from your inspection department. I know that paint chips in different gloss ranges for color drift control are commercially available. I have not seen them in different textures. One source for textured paint chips is the paint companies that supply your suppliers. The formulation companies are equipped and able to apply their paints using varying spraying techniques to produce varying textures. If you specify the paint to be used on your products, ask your favorite paint supplier to provide the chips. Another source is the spray equipment suppliers. Unfortunately, there is no industry standard, per se, for paint texture. Unless there happens to be a standard for paint texture on products in your industry, you must decide what is acceptable to you. I suggest the following course of action: 1) Have a number of chips prepared with a range of textures. 2) Decide what texture you want on your products. 3) Provide paint chips having the desired texture to your suppliers and your inspection department. A. The answer to M.M.'s question in the January 2003 issue of Painting Clinic is still valid today—paint texture standards 38 NOVEMBER 2013 — are still not available. However, there is another standard you may be able to use. Distinctness of Image (DOI) standards are available for paints having fairly glossy surfaces. If there is orange peel or any other type of surface texture present on the paint surface, a reflected image would not be as "distinct" or as clear as it would be on a mirrorlike, "smooth" paint surface. However, there must be a reasonable amount of gloss on the surface to see reflected images. CARL IZZO / Consultant DOI standards may suit your purposes, and I suggest investigating this approach to your problem. I still believe having your own texture standards for use by your outside supplier and by your inspection department is a better idea, however. Reader Response to Hard, Abrasion-Resistant Coating Q. M.W.'s question in the September edition of Painting Clinic about "Hard, Abrasion-Resistant Coatings" doesn't identify the plastic substrate that influences the type of coating selected. It also doesn't state whether it was pigmented or clear. For maximum hardness and abrasion resistance, I would select a molded-in color matched to the cool gray Pantone color, utilizing a polycarbonate substrate so that baking could be done if the technology selected required it. A clear coat could then be applied. Three technologies come to mind: 1. UV-curable coatings such as those used on polycarbonate automotive headlight lenses would work. This would require infrared flash and UV lamps to cure. Other lower-temperature and lower-cost substrates besides polycarbonate could be used, too. 2. A polysiloxane coating such as those used on eyeglasses, ski goggles and safety shields would work, but would require curing temperatures of around 230°F, which would necessitate the use of a polycarbonate substrate. 3. A polyurethane coating could be either clear or pigmented. A pigmented coating would, of course, eliminate the need to color match the substrate, and a lowerheat-resistant substrate could also be used. Maximum cure, even with baking, is achieved after two weeks. Perhaps a basecoat and clearcoat combination could do the job with this type of technology.

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