Anodizing Vs. Powder Coat

I am an engineer on a large yacht build project and urgently need information and advice on choosing a finish for the aluminum deck plates in the engine room.


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Q. I am an engineer on a large yacht build project and urgently need information and advice on choosing a finish for the aluminum deck plates in the engine room. The yard has specified an anodized finish, but because of previous experience with anodizing I am considering having the plates powder coated instead. In the past, oil, fuels and cleaning soaps have always left marks on the plates which are sometimes very difficult if not impossible to remove. Should the anodizing become chipped, this too is difficult to repair. The shipyard has never powder coated deck plates in the past and they are quite reluctant to undertake the process, but I think that powder coating will provide a better and more durable finish than anodizing. Can you help? S.R.

 

A. Anodizing is an inorganic finish, while powder coating is an organic finish. Powder coatings are some of the best organic finishes (paints) on the market. However, they cannot withstand the same abuse as inorganic finishes, such as plating or anodizing. Inorganic finishes have superior hardness and scratch resistance properties when compare to organic finishes. Corrosion resistance is also better with inorganic finishes.

This begs the question: “If inorganic finishes are so good, why are they not used more frequently?” The simple answer is environmental compliance. When was the last time you saw chrome bumpers on a car? Everyone agrees chrome bumpers outperform painted bumpers, at least for scratch resistance and hardness.

The simple answer is: chrome or nickel plating have many hazardous waste products that are inherent to the application process. I am sure that the weight savings of using a plastic painted bumper over a heavy metal bumper has a lot to do with this decision, as well.

My advice is to stick with anodizing your deck plates, as your customer will be very unhappy with their powder coated substitutes. By all means, if you are looking for an organic finish substitute for cleats, window trim, hardware parts, etc., then look at powder coating. Powder coated products have been successfully used in these applications in the boating industry for many years.

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