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Mag Seal: Daiwa’s answer to waterproofing spinning reels without sacrificing rotor rotation smoothness.

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Will this be the future for protecting spinning reels from corrosive saltwater? FiSH On! checks out the use of ferrofluid in Daiwa’s Mag Seal technology.

Daiwa first introduced its Mag Sealed concept in its Certate line of spinning reels in 2010 and has since expanded the use of this technology to its other range of spinning reels such as the Saltiga and more recently, the new Caldia spinning reel. In its essence, the Mag Seal technology is a unique waterproofing design that involves the use of ferrofluid to form a seal to prevent water seeping into the gears via the rotor and pinion gear assembly.

In a simplified definition, ferrofluid is a liquid that quickly becomes magnetized in the presence of a magnetic field. Picture a liquid substance consisting of very fine, nanoscale particles of iron that is attracted to magnets. This ferrofluid is typically liquid in form but will quickly respond and align when it comes into close proximity of a magnetic force.

Ferrofluids were first discovered in the 1960’s at the NASA Research Center when scientists were investigating various possible methods of transferring liquid fuel in a gravity-free outer space environment. Over the years, the use of ferrofluids gradually found their commercial application in medicine, manufacturing, aerospace, instrumentation and many other sectors. In fact, ferrofluid is used in disk drive manufacturing as an effective rotating shaft seal to keep dust particles or other impurities from entering disk drives through tiny gaps around the rotating drive shafts. Similarly, Daiwa has adopted this same principle in ferrofluid sealing in its Mag Sealed concept.

As we know, saltwater is bad news for reels especially when left exposed for prolonged periods. Washing under running tapwater typically removes excess salt but minute amounts diluted with tapwater can still seep through into a reel’s gearbox. Over time, corrosion kicks in and eventually causes havoc with the gears and bearings. Water normally finds its way into a spinning reel’s gearbox via a very minute gap between the rotor and opening of the body. Strategically sealing this gap with rubber gaskets or O-rings can significantly reduce the possibility of water entry but the downside of this solution is the existence of cranking inertia. There is a sense of slight resistance when engaging the reel handle. While this is negligible when cranking under load, it is rather noticeable during free spin compared to a reel without such sealing. Constant friction also wears these seals out over time, which eventually allows water penetration into the reel’s gear works.

Mag Seal in a Certate

Mag-seal under the rotor of a Daiwa Certate
(NOTE: do not attempt to disassemble the reel on your own as the ferrofluid will leak)


Closer look at the Mag-seal

Daiwa’s ferrofluid, which it calls Mag Oil, is used in conjunction with a magnet placed perpendicularly in the rotor frame. The magnetic flux causes the ferrofluid to ‘stick’ between the body and rotor to create a liquid barrier to seal the minute gap and prevent water entry. This clever design replaces rubber seals around the pinion assembly for waterproofing while effectively eliminating friction and allowing free, unobstructed and smooth rotor movement.

The adoption of ferrofluid by Daiwa as an effective waterproof seal is a big step forward in sportfishing tackle innovation. While this solution may not be quite cost-effective as of now to fully replace the more economical O-rings and rubber seals in other open moving parts of fishing reels, we can certainly expect to see this as a stepping-stone for future breakthroughs in tackle innovation.

Daniel Wan has been fishing since the age of 12 and has a deep passion for fishing with artificial lures – especially light-tackle jigging. Previously working for two multinational IT companies, Daniel left the IT industry to follow his passion for fishing, photography and writing.