How can Stainless Steel rust?

The stainless rusting issue pops up now and then and the accusation is often made that cheap material is being used in a money saving effort. Even though that seems to be a logical explanation it’s not really true. When it comes to marine parts made of stainless I’ve never really seen a “cheap” alternative from any of the suppliers.

 Speaking of suppliers, there is a relatively small selection of suppliers of hardware dedicated to boat building, and from that group an even smaller collection of them are what we call preferred suppliers. Most of the major builders of boats in the US use the same group of preferred suppliers and do so as a buying group to better control pricing. Because of that the quality of the cleat, or the hinge, or latch that goes on a Whaler for instance is the same as the one that goes on a Key West. They come from the same source, in the same box, and often on the same shipper, landing in a warehouse where they are distributed to the various builders.

Bottom line, if the material is rusting on one brand and not on another, there’s another explanation rather than quality or cost. While that is a fact having the consumer with rusted material to understand that is the tough part. Since I am obviously susceptible to bias in an explanation I go to the internet for help. In the search box I enter, “How can SS rust”. The following header pops up with over a million results. The first dozen or so are very good explanations. One of the best technical explanations is the second link below.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=how%20can%20stainless%20steel%20rust

http://www.sperkoengineering.com/html/Rust.pdf

While this PDF is directed at industrial applications the chemical properties of stainless apply across the board. Of particular interest is the ferrous material that can be introduced to the surface of the stainless material starting the rust process. How can that apply to the hardware on a boat?

In the water used to wash the boat, surprisingly. Most of us have seen the rust stained sidewalk or driveway where the irrigation water splashes over from the grass. The same iron in that water can end up on the hardware on a boat causing it to rust. In cases where the water has ferrous material suspended it would b better to wash the boat with salt water instead. I’ve seen cases where every piece of stainless on the boat was rusted and it was traced back to the well water used to rinse the boat diligently after each use. That customer was convinced that we used cheap material to save money. Sometimes it’s just the water.

  A discussion forum for Bradenton resulted in the post at this link. http://www.city-data.com/forum/sarasota-bradenton-venice-area/339596-city-water-vs-well-water-2.html and the latest 2014 water quality report for city water listed salt and minerals as contaminants.

How to combat that is the question. Each boat owner’s packet comes with a stainless care instructional in the owner’s bag. I’d also suggest a towel dry concentrating on the hardware, as well as some sort of anti corrosion treatment. To remove the rust I suggest a mild abrasive stainless polish such as AERO disinfectant cream cleanser available from Aero Chemical Co., Atlanta Ga.