April 06, 2021
By Dr. Jason Halfen
Contemporary anglers have three distinct options when spooling line onto reels: monofilaments, braids and fluorocarbons. Each is fundamentally different from the others and possesses its own particular strengths and weaknesses. Many of these differences are rooted in the unique chemistry and manufacturing processes used to prepare the three line varieties, making each particularly well suited for specific presentations.
In recent years, advances in fluorocarbon line design and engineering have dramatically enhanced the scope of its applications in both fresh- and saltwater angling. Let’s explore the factors that make fluorocarbon a must-use line option whenever you hit the water.
Fluorocarbon line traces its origins to 1971, when chemists and engineers at Kureha—a Japanese specialty chemicals firm—first extruded fluorocarbon fishing lines from raw polyvinylidene fluoride resins and launched the company we now recognize as Seaguar. Early users of fluorocarbon quickly recognized many of its unique properties—attributes that helped them hook and land more fish—and these advantages have continued to build over the past 50 years.
One of the first things you’ll appreciate when using fluorocarbon is that it’s nearly invisible underwater to anglers and, more importantly, fish. This is not hype and hyperbole, but science and fact. The extremely low subsurface visibility of fluorocarbon is rooted in the optical property of refraction, which describes the speed of light as it travels through a particular medium. Because the refractive index of fluorocarbon (1.42) very closely matches that of water (1.33), fluorocarbon is quite difficult to see beneath the waves. By comparison, traditional nylon monofilament line has a much higher refractive index (1.58), rendering even clear monofilaments much easier to visualize, by both anglers and fish, in the water.
"One of the reasons that fluorocarbon use has grown explosively during the past decade is that anglers have recognized the advantages of an extremely low visibility line," says Seaguar General Manager Gerry Benedicto. "Many lakes and rivers across the country have gin-clear water that allows fish to see basically everything, so when you have a line that is virtually invisible underwater, it’s game on!"
The polymers used to prepare fluorocarbon lines impart other unique physical and chemical properties to these fishy filaments. Specifically, the fluorine-rich nature of their synthetic starting materials render fluorocarbon lines uniquely water-repellent and resistant to the damaging effect of exposure to ultraviolet light from the sun. These properties stand in stark contrast to those of nylon monofilaments, which can absorb as much as 10 percent of their weight in water, and lose up to 20 percent of their original strength after 100 hours of exposure to ultraviolet light. If you want to fish with a line that’s designed to stand the test of time, fluorocarbon is the obvious choice.
What else will you notice when you start fishing with fluorocarbon? First, unlike mono and braid, fluorocarbon lines sink in water, a result of their density (nearly 1.8 g/ml) being substantially higher than that of the water (1.0 g/ml) we cast them into. This means your baits, especially lightweight finesse presentations like the Ned rig, will fall into the strike zone faster and stay there longer.
In addition, fluorocarbon lines offer just the right amount of stretch, positioned between nylon mono, which can stretch up to 25 percent of its original length, and completely no-stretch braided lines. As a result, fluorocarbon will yield positive hooksets at long distances, while still providing a measure of trophy-saving shock absorption when a big fish makes a powerful run at boat side.
Anglers fishing with fluorocarbon have two options when spooling up: running straight fluoro or using a braided main line linked to a fluorocarbon leader. If you plan to use a fluorocarbon leader in this way, learn to tie a quality braid-to-fluoro knot so you can quickly add a fresh leader should yours become damaged during the heat of battle. The FG, double-uni and Crazy Alberto knots are all good ones.
Many bass anglers will fill a baitcasting reel with 12- or 15-pound-test fluorocarbon when presenting crankbaits, taking advantage of fluoro’s significant abrasion resistance (another beneficial consequence of all of those fluorine atoms) to protect their line’s integrity as the bait deflects erratically off rocks and wood. At other times, spooling up with a silky-smooth, eight-strand braided line in 20-pound test and finishing with a 4-foot leader of 8-pound-test fluorocarbon can launch lightweight presentations into the stratosphere and reach hungry fish that other anglers cannot tempt.
One of the unique attributes of fluorocarbon lines is that their properties are completely dictated by the specialty resins used in their manufacture.
"The quality of fluorocarbon has evolved so much over the last 10 to 15 years," notes Benedicto. "Older formulations of the line were stiffer, making line management challenging and knot tying less forgiving. But now, fluoro is much softer allowing for better castability and sensitivity. At Seaguar, we even have custom resins that can be formulated to create fluorocarbon lines that cater to different fishing applications and techniques. With fluorocarbon, the sky truly is the limit."