Paint Materials Guide - Color Chemistry

Understanding Paint Top-Coat Materials

Steve Dulcich May 25, 2010 0 Comment(s)
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Clear coats can add to the durability, environmental and chemical resistance, and brilliance of shine in paint's finish. Further, clear can typically be fine-sanded and machine polished for a nearly perfect and glass-smooth surface. With those characteristics recommending a clear-coat finish, it's not hard to see why the use of clear has become almost universal in high-end custom paintwork. Modern clear coats developed back in the '70s, about the same time as the modern catalyzed acrylic enamels and polyurethanes (DuPont Imron) came on the scene. Using a similar catalyzed clear formulation, custom painters found they could achieve previously unimaginable levels of gloss and depth by applying clear over the catalyzed acrylic enamel or polyurethane paints. These early two-stage clear-coat paint systems were applied wet-on-wet, where the high-gloss catalyzed acrylic enamel was sprayed as normal, allowed to solvent flash, and then followed with the clear coats.

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Later, the rather cumbersome early two-stage system developed into using a flat, low-gloss, and fast-drying basecoat followed by the clear, rather than starting with the high-gloss catalyzed full-gloss paint. This is the basis of the popular base/clear two-stage systems that are the mainstay of automotive refinishing today. With the base/clear system, the base contains the pigments and color properties only, and the product sprays on with a very quick dry time, much like a lacquer. All of the gloss and translucence are properties of the clear coat. With this system, the easy-to-apply base color coat minimizes the potential for problems or flaws in the color application, while the clear can be burnished and buffed to provide a spectacular, show-car sheen.

Which is the best approach in refinishing your Corvette-single- or two-stage? It all depends upon the goals of the paint project. For a true OEM restoration, the two-stage option is definitely out. Even if trying to "authentically" duplicate a representation of the OEM finish using modern materials, a single-stage paint approach is more authentic. However, if the goal is a mirror-smooth surface with paintwork that "pops" like no factory machine ever did, a clear-coat paint approach is normally the correct choice. Some painters, however, will still select a single-stage paint approach when refinishing in a solid color, particularly black or even white. With modern single-stage urethanes, solid colors can be color-sanded and polished to a mirror finish as though they are clear-coated, and some consider the clarity of these colors to be superior using the single-stage technique.

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No matter which material you select for your Corvette refinishing project, whether an authentic acrylic lacquer OEM restoration or a gleaming custom base/clear urethane approach, select a high-quality manufacturer for the material and follow the recommendations. All of the major paint manufacturers will carry a full line of primer and undercoat products, often providing a system to take the surface from fiberglass to fully finished. Included here will be the primers used for adhesion, filling, and sealing the surface before paint. Manufacturers will often publish this product data on the material specifications sheet for the topcoat system being considered. Read up on the technical information directly from the paint manufacturers, and solicit some helpful advice from your professional paint retailer or supplier.

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