Aluminum oxide paint
Early in my career I worked for a dealership that sold production boats, every one of which was equipped with painted aluminum arches. Invariably, the paint would blister, in some cases before the vessels were offloaded from delivery trailers, and warranty claims were dutifully submitted, which the builder, to its credit, promptly paid. In an effort to stem the cash flow, the company earnestly focused on improving the preparation and paint application processes. Yet the problem persisted.
A few years later, I was managing a boatyard where painting aluminum spars was common. Leery of experiencing the same sort of failure, I began reviewing old spars and other painted aluminum hardware. I noticed that nearly all the failures occurred adjacent to a hardware installation, a fastener, a spreader, a step, or some other fitting—an area where the paint coating had necessarily been upset or breached. I believed I was onto something.
Steve D’Antonio (all)
It’s the rare marine industry professional who hasn’t come across unsightly blistered paint on aluminum surfaces. Here, the screws damaged the paint when they were installed, allowing water to migrate under the coating.
Among other attributes, marine-grade aluminum alloys, those in the 5000 and 6000 series, are naturally corrosion resistant. When exposed to air, oxygenated seawater, or fresh water, aluminum quickly develops a tough, transparent oxide film that is resistant to corrosion. There is, however, an aesthetic price for this durability. Left to the elements, aluminum develops a dull gray—and eventually dusty, gritty—finish; for military, pilot, fishing, and utilitarian applications, that finish can be a thing of beauty, as it lowers building and maintenance costs. Few recreational users have, however, learned to look beyond aluminum’s blemished surface.
The white powdery material, aluminum oxide, forms when aluminum is robbed of oxygen in a wet environment.
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