Cleaning Q&A: Salt Removal

Q. Can you refer me to someone who can help locate documentation on cleaning salt from surfaces after exposure to seawater? Typically it occurs on anodized aluminum and other marine alloys.

A. You may want to inspect the surfaces of interest since it is likely there is more than simple salt left behind from seawater. The salts dissolved in seawater would resolubilize if your parts were simply rinsed or immersed in fresh water. Warm water will dissolve more of the salt, but ambient water should still dissolve a significant amount of it. Assuming you have tried this and still notice some residue that appears salty, it is likely that you see some amount of corrosion product that is left behind from the attack of the salt water on the aluminum and other alloys.

In this case, the cleaning involved will be more difficult for removal of the corrosion product, especially if doing it safely with minimal attack of the base material. If you are trained in the use of nitric acid, that can be an effective means of removal of corrosion product from aluminum, but may be damaging to other seawater alloys such as copper-nickel. You should have the right training and background in the use of nitric acid before attempting this and will need to consider disposal options when dealing with a large quantity of material and waste.

Originally published in the October 2015 issue.