Have you ever wondered what happens to a magnet when it’s used near or fully emerged in saltwater? First, you might consider what you know about the relationship between magnets and freshwater, which is considered slightly diamagnetic. This means it creates a weak oppositional magnetic field to an applied magnetic field.  However, if you add salt to the mix, the water’s magnetic field completely ceases to have any significant impact on other magnetic fields. Salt also lowers the boiling point, raises the freezing point, and strengthens water’s electrical conductivity. This means saltwater affects magnets differently than freshwater.

Saltwater and Electromagnets

Saltwater conducts electricity more efficiently than freshwater, and its conductive properties create a moving magnetic field when an electromagnet is placed nearby. Then, the saltwater creates an opposing magnetic field, causing turbulence (erratic changes in pressure and flow velocity) in the water. When a charged magnet comes into contact with saltwater, the ions flow through the metal to become stabilized, resulting in the electrical field. 

Corrosion of Permanent Magnets

While Apex does not sell electromagnets, we do have an assortment of permanent magnets. These include Ceramic ferrite, samarium-cobalt, and neodymium magnets. As many people are aware, magnets typically react to moisture by rusting. Saltwater — whether the magnet is fully immersed or simply operating in saltwater air — can cause even more serious corrosive damage that can actually weaken a magnet’s strength. If you use certain types of magnets within saltwater or a high-moisture environment, you’ll likely have to replace them on a regular basis. For example, the high iron content in neodymium magnets makes them more vulnerable to moisture.  It is possible, however, to order neodymium magnets coated in a layer of protective material like rubber or epoxy.  Samarium cobalt magnets are the most resistant to corrosion, even without a layer of protection. They’re often used in marine, boating, and offshore applications because they cope well with corrosive saltwater.  While alnico and ceramic magnets both resist corrosion as well, they don’t have the same level of strength as either neodymium or samarium-cobalt.

Apex Magnets Used in Saltwater

Our valued customer Chris Anest, who has been fishing off the coast of Japan for the last 16 years, needed something to hold his 8oz lures without damaging his expensive rod. Any magnets he used would be exposed to saltwater and still need to operate effectively.  Anest decided to mortise our samarium-cobalt magnets into PVC pipes as a method of holding his lures in place while navigating the choppy seas. His innovative method paid off, and his Apex magnets have maintained their strength despite the corrosive nature of the sea. He says that these days, he constructs that same rod and lure holders for fellow fishermen. We genuinely enjoy helping people like Chris come up with creative solutions to their problems, so if you think magnets might be able to help you, contact us today. We can walk through the variables that make certain magnets better for one application versus another.