APPLYING FINISHES OVER EPOXY COATED SURFACES | |
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All exposed epoxy surfaces should be painted or varnished with a high ultra-violet (U-V) resistant varnish to protect the surface against potential long-term breakdown from U-V radiation, a phenomenon which occurs with all boatbuilding resins. POXY-SHIELD® provides an excellent paint base for most paints and varnishes, even though varnished coatings will still require periodic renewal. Interior areas not exposed to sunlight can be completely coated and finished with resin alone, and in many cases, this can be done PRIOR to putting interior components in the boat. While marine paint system technology is a rapidly advancing field where direct unqualified statements may be subject to change and revision in a relatively short period, in general, just about any paint commonly used on boats can be used on boats made with the GLEN-L EPOXY ENCAPSULATION SYSTEM. These include the standard-type marine enamels, silicon/alkyd types, epoxy paints, and the one or two-part urethanes. With many marine paints, manufacturers recommend an "etching" primer over polyester or epoxy coated surfaces, with or without fiberglass. Linear polyurethane (LP) systems can usually be applied directly over epoxy coated surfaces without primers, but they are costly and frequently have much more critical application parameters. Many brands and types of marine paints are available which are suitable for roller or brush application by the amateur. Marine paints are extremely durable, and most give a high-quality "yacht finish". Marine paints and varnishes are formulated to stand up to gasoline and other solvents found in a marine environment as well as the strong, direct and reflected, ultra-violet light. While expensive at first, marine paints may be less so over the long term because these finishes last longer in a marine environment. Remember that if your boat remains in the water for long periods, it will require an anti-fouling type bottom paint. An alternative to marine paint systems, particularly on smaller, low budget boats, are industrial grade alkyd enamels. Like marine paints these paints may not be available in local consumer paint stores and may take some searching to find. As in all cases with various paint products, always follow the instructions provided by the paint manufacturer to the letter. lf questions arise, contact the paint manufacturer directly for his advice, since most firms have highly qualified technical staffs that will know how to answer questions. As a general rule, we advise against spray application of paint systems unless already an expert and has the proper facilities to assure sound, safe results. With a good paint system, properly applied, excellent results are possible by the amateur without using spraying methods (rollers and brushes work well with many systems). Some builders ask the question about pigmenting one or all of the various coats of POXY-SHIELD® used with the GLEN-L Epoxy Encapsulation System. Pigments should not be used with the first coat as this can effect penetration ability. Pigmenting of the resin is optional and has drawbacks as well as a couple of advantages. Any pigment used must be compatible with epoxy resins. Pigmenting may increase the viscosity of the resin so don't add more than about 2% by volume. The depth and intensity of most pigments are not enough to eliminate the need for paints which have much higher pigment content. Also, pigments may decrease the resin's moisture absorbing resistance. The addition of pigments will not make resin into a paint; it will still need to be sanded, sometimes resulting in an uneven color. Adding pigments can serve as a guide when sanding a coat of resin, since over-sanded areas turn lighter indicating that no more sanding should be done in that area. Pigments also allow visual control of the coating thickness being applied. Pigments can also be added to the final coating to match the color of the final paint system, giving a pre-colored paint base perhaps eliminating the need for undercoats. In short, pigments can be used, but they are far from a necessity, and will not eliminate the need for a final paint coating. Before doing any finish work or applying finishes, allow the last coat of epoxy to cure 5 to 7 days at 70oF, longer at colder temperatures. Wipe down the hull with a water/ammonia dampened rag or sponge. This will eliminate the greasy feeling amine blush to make final finish sanding easier and minimize clogging of the abrasive. lf you have been careful in your application of resin with all coats, making sure each is evenly applied, and have taken care to prevent runs and sags, and to correct mistakes along the way, the finishing process should be relatively easy. Final finish work will vary depending on the quality of surface which is desired, whether the surface will be naturally finished or painted, and whether or not a sanding undercoat will be used. Final finish sanding is usually done with either an orbital sander or hand sanding block. lf you wish to use a disc sander, equip it with one of the foam backing disc pads which will minimize gouges. lf you have not used a disc sander, some practice may be in order since these can easily damage a surface. The rpm of the disc sander should be kept relatively low (around 2000 rpm) since it is possible to scorch the resin surface if rpm's are too high. Start out sanding with a 60 to 80 grit open coat paper, advancing to a 120 to 180 grit. For many builders, this will yield good enough results for painting, but for a high-gloss natural finish, work up through finer grits as required, ending off with a 220 to 280 or even finer grit wet-or-dry paper using wet sanding techniques. Be careful not to remove too much resin by sanding, and if it looks as though too much sanding will have to be done, it may be better to apply more coats of POXY-SHIELD®. Note that POXY-SHIELD® will not in itself provide a perfect "bar top" finish, even when flow coating. Although the epoxy has high gloss properties, it is not a final finish. An ultimate final high-gloss brightwork finish is best achieved through finish sanding and coating with varnish or comparable clear coating products, and such is required for all exterior use for U-V protection. lf using varnish, apply at least two coats (more is usually better) of a U-V stabilized varnish or clear polyurethane product. lf your surfaces are to be naturally finished, it is preferred to use only Fast hardener for all coats for a faster cure and better long-term clarity. lf the resin cures more slowly, such as with the use of the Slow hardeners, a potential exists for clouding of the clear coating in the presence of moisture. 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