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The Right Way to Paint - Page 2

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Part 2: Interprotect was originally developed to prevent and deal with osmotic blistering on fiberglass hulls.


Photo: Jerry Wyszatycki

Next comes the primer, which Purtell claims is Interlux’s strong suit. The E in its Interprotect 2000E/2001E Epoxy Primer stands for “environmentally preferred,” indicating it contains no methylene chloride, a volatile, colorless liquid that’s considered a potential carcinogen by both the Occupational Safety and Health Administration and the Environmental Protection Agency.

Interprotect was originally developed to prevent and deal with osmotic blistering on fiberglass hulls. It incorporates a “microplating” system in which microscopic plates overlap one another much like the back of an armadillo, robbing water of a direct path through the coating. Purtell says this is unlike other epoxy paints, in which particles arrange themselves randomly.

Not only do these plates repel moisture like a shingled roof, but they also help resist sagging. This is key to Interprotect’s user-friendliness. (Two-part paints are notorious for their tendency to slowly sag, so by the time you notice, the paint is too dry to brush out.) Yet another benefit for the do-it-yourselfer is Interprotect’s extended recoat time: up to 14 days. Two-part paints usually have a maximum recoat window of just 24 hours; after that you must sand them before applying another coat.

Interprotect comes in kit form, so you’ll need to mix the components well and in the proper ratio, then leave the mixture to “sweat in” (referred to as induction time) for 20 minutes. This also allows any air bubbles in the mix to rise to the surface and dissipate.

Apply the first coat after you’ve allowed the Primewash to dry for about an hour. Unlike the opaque coat of Primewash, Interprotect is a solid surface. To achieve the required 10-mil thickness, Interlux suggests applying four coats, with two to three hours between applications. A solvent-resistant, four-inch foam roller combined with a a two- to three-inch disposable bristle brush for cut-in areas is the best combination for achieving a proper, uniform thickness.

By the time the last Interprotect coat went onto our Sea Ray, I had to admit that the running gear was looking bulletproof. The time it took the paint to dry gave me a chance to talk with Purtell about a couple of important related issues. The first is galvanic corrosion; as he succinctly put it, “If your zincs are gone, the next victim is the paint.” But don’t add zincs simply because you think more is better; as Purtell says, “Maintaining proper hull potential is crucial for keeping coatings intact.”

Also, if you have to do some sanding—say, a few bugs kamikazed themselves into the wet paint or an untimely gust of wind kicked up some dust—it’s essential that you don’t “burn through” the areas where the edges and corners are sharp. A foam sanding pad will adequately scuff up or flatten out a piece of debris without removing too much paint. Remember, maintaining that uniform 10-mil thickness—which can be difficult on the curved surfaces of running gear—is critical to maximizing the life of the job.