Alloy At Risk
When it comes to metals in marine applications, most boaters think of stainless steel. But aluminum is also a good choice. It’s lightweight, relatively inexpensive and strong, and doesn’t rust, which is why it’s used for T-tops, tuna towers, ladders, railings, and hulls. But even marine-grade aluminum is no match for the saltwater environment unless it receives proper care. And though aluminum won’t rust, it can become pitted, leaving your boat looking downright ugly.
Once corrosion has taken hold on aluminum it’s hard to treat so prevention is crucial. The two most effective ways to protect aluminum from corrosion are anodizing and powder coating. Both are highly involved processes that must be performed by a professional.
Anodizing (above) involves immersing aluminum into an acid bath and subjecting it to an electric current. The aluminum becomes the anode (positive pole) and the acid becomes the cathode (negative pole), causing the aluminum to oxidize thereby creating a durable coating that can range from matte to high gloss.
Powder coating is a dry process using a special powder that’s sprayed onto the aluminum, then baked at 325˚F to 375˚F for 12 to 20 minutes. The resulting skin coat is more durable than regular paint. Generally, anodizing produces a less attractive but more durable finish than powder coating, which creates a shiny surface that can be scratched or gouged.
Once it’s applied, powder coating is simple to maintain: Remove soot, salt, and grime by washing with a neutral detergent and rinsing with fresh water. The same is true of anodized aluminum although here you can use a mild abrasive cleaner for difficult stains and deposits.
If you don’t want to spend the money to have your aluminum anodized or powder-coated, you can still keep it looking good by maintaining it yourself. In fact with a little time and elbow grease you can have your aluminum components looking almost like they just came back from a commercial polisher.
A number of products do a good job of cleaning and protecting aluminum. Nevr-Dull (www.nevrdull.com) is a specially treated wad of cotton cloth that comes in a can. Tear off a piece and rub it thoroughly on the area that needs cleaning. Wait a couple of minutes, then wipe off the foggy finish with a clean towel. Nevr-Dull requires considerable elbow grease and doesn’t offer much protection against the elements, but it’s relatively easy to use and removes tarnish, water spots, and dirt quickly. Nevr-Dull is available at hardware and marine-supply stores and sells for under $10.
Rupp Marine (www.ruppmarine.com) makes Aluma Guard, a spray that it says prevents pitting and corrosion and restores aluminum’s natural shine. Boaters I’ve spoken with say it works well and leaves aluminum looking polished and new, but I’ve also heard reports that it runs and leaves streak marks if it gets wet before it’s dry. A 16-ounce bottle sells for around $12.
Finally, there’s the two-step system developed by Woody Wax called Triple XXX (www.woody-wax.com). The first application is designed to remove corrosion and dullness from aluminum with little rubbing and buffing. The second application is a hard wax made to enhance the shine and create a barrier against salt, pollution, and water spots. A 16-ounce tub of Woody Wax retails for about $26.
This article originally appeared in the March 2009 issue of Power & Motoryacht magazine.