Metal finishing Q&As since 1989

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Best Coating for Gasoline/Salt Corrosion but Lower Cost than EN?

We have a mild steel part currently EN plated, which does a fine job vs gasoline and salt spray - used in an outboard engine application. We are looking for a cost-reduction, however. What is the most cost effective coating that can withstand 400 Hrs of salt spray (and lots of hours vs gasoline?)....thanks..

John Walters
Designer - Newport News, Virginia
2007

Speaking on behalf of the many recreational boat owners who pay five or six figures for a boat and motors you need to know that we don't care if we pay a few more dollars for components that perform better and last longer. Towing, hauling and repairs for boats and motors are VERY expensive. Not to mention risking time lost on the water, being broken down sixty miles offshore, facing inclement weather or in harms way.

Todd Osmolski
- Charlotte, North Carolina, USA
2007

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Well said, Todd. Without making a detailed study, my own experience from living on the salt water for many years is that boats need to be towed somewhere between 100 and 1000 times as often as cars for every mile driven. If ever there was an industry plagued by low quality, that hasn't earned the right to even think about cost reduction programs yet, it is recreational boating :-)

John, on another note, please do not attempt to use "400 hours salt spray" as a gauge for a substitute finish. Salt spray testing is a QA measure that is used to make sure your process hasn't gone south -- it is not a predictor of real world life because the corrosion mechanisms in real life are different. There are many examples of finishes that perform poorly in salt spray testing and well in the real world, and vice versa; for example, galvanizing can last 50 years in the real world while offering poor salt spray resistance.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007