Best Fluorocarbon Fishing Lines Reviewed: Using Fluorocarbon as a Main Line

Why Choose Fluorocarbon as a Main Line?

Fluorocarbon is a monofilament composed of polyvinylidene fluoride (PVDF). Essentially a type of thermoplastic, it’s both harder and denser than nylon. In theory, this makes fluorocarbon -diameter for diameter - more abrasion resistant than standard mono. It also improves its sink rate and sensitivity.

High-quality fluorocarbon lines are multi-layered affairs, with a strong core to improve strength. They’re also usually coated to improve abrasion resistance, improving their handling and casting performance, too.

Pros

Waterproof - Fluorocarbon is completely waterproof. As a result, it won’t change its handling characteristics or weaken when wet. With the exception of knotting, it performs identically, wet or dry.

UV resistance - Your gear spends a lot of time in the sun, and that UV exposure is punishing to nylon monofilament. But fluoro is vastly more resistant to UV break-down than nylon, meaning that you can count on the fluoro to last longer without needing to be changed.

Sinks - Being much denser than water, unlike mono, fluorocarbon sinks. This is often given as a reason to switch to fluoro--but while true, its actual rate of descent is very, very slow. Take a look at this chart, for instance. Fluorocarbon takes a full 15 seconds to drop one foot!

As Mark Romanack of Precision Trolling explains, “the sink rate of fluorocarbon is so modest that it has next to zero impact on how deep a crankbait or other piece of trolling gear will dive.”

Sensitivity - That high density also gives fluorocarbon better sensitivity than mono, and this characteristic is further enhanced by its relative stiffness. It also provides exceptional slack line sensitivity--a huge feature for many bass anglers who fish bottom contact techniques.

In fact, this really is the strong suit of fluorocarbon, as it can perform like braid in this respect, without the high-visibility of a superline.

Maybes

Low-visibility? - The primary selling point of fluorocarbon is its supposed near-invisibility in water. Indeed, its manufacturers and fans suggest that its low refractive index means that it’s nearly invisible to fish. Essentially, light is bent and slowed by fluoro much like it is in water, and the idea is that this makes it very hard to see.

An easy test of this property recommends that you dip clear fluorocarbon and mono of the same diameter in a glass of water; when compared side-by-side, the fluoro is generally the less visible.

Unfortunately, that’s not really the whole story. As fishing photographers report, mono and fluro are indistinguishable to their cameras.

It’s also worth noting that scientists insist that fluoro is NOT nearly invisible in water. They’ve done the physics, and the answer is pretty clear: fluorocarbon isn’t what its manufacturers claim.

Still, it may make a difference in some situations and with some fish. In fact, when TackleTour tested Seaguar’s fluorocarbon in the real world, they found that it improved strike frequency with salmon, but that mono outperformed it on striped bass.

Rob Hughes summarizes our view pretty well. “Flouro [sic] is a brilliant material for a number of reasons, but assuming that it is invisible is a recipe for disaster.”

Low-stretch? - As fluoro fishermen know, the line stretches under load. Various brands stretch more or less, but generally speaking, fluorocarbon stretches more than mono, but it takes more load to force it to give in the first place. That said, unlike mono, it tends to retain that elongation, permanently deforming as a result.

Take a look at these charts:

As Berkley says, fluorocarbon “actually stretches more than nylon mono. The difference is, it takes a greater force to get fluoro stretching in the first place. As a result, fluoro makes a fine choice for situations where controlled stretch is helpful, whether as a mainline or a leader in conjunction with low-stretch superline.”

Rapala disagrees slightly, reaffirming the idea that brands matter. “Fluorocarbon does have less stretch (average 25%) than most nylon monofilaments (average 28%) but the difference is nearly [in]discernable by anglers until the nylon begins to absorb water and become more elastic.”

Cons

UV resistant - Don’t dump your discarded fluorocarbon in the water! Because it resists UV degradation, it’ll hang around for a long, long time.

Cost - Fluoro is expensive to manufacture, and that cost is passed down to consumers.

Hard to tie and low knot strength - If fluorocarbon has an Achilles’ heel, it’s knotting. Because its basic material is hard, it doesn’t bite well on itself, leading to both difficulty tying and poor knot strength.

In TackleTour’s testing, the high-end fluorocarbons they reviewed experienced knot failure at an average of 63.5 percent of their tested tensile strength. That means that for the average 20-pound fluorocarbon, knot failure will begin at just 12.7 pounds of force!

Which knots are best with fluoro? We recommend the Palomar.

This notwithstanding, there are excellent fluorocarbon lines that rival nylon monofilament in knot strength. This is unusual, and most do not.

Casts poorly - Fluoro’s stiffness is not helpful here, either, and it generally casts worse than both mono and braid. Moreover, because it’s exceptionally hard, it creates more guide friction.

Again, there are exceptions, and we review some really limp, easy casting fluoro among our favorites.

Not as abrasion resistant as people suggest -PVDF is amazingly tough material, and given that fluorocarbon is a round monofilament, it can take some abuse, sliding over abrasive surfaces.

But fluoro isn’t necessarily tougher than nylon mono, and manufacturers don’t say that it is. Instead, they suggest that because of its supposed “low visibility,” anglers can run heavier weight line, resulting in greater abrasion resistance simply because of increased diameter.

Careful testing hasn’t verified this supposed abrasion resistance, either.

Watch this video to see what we mean:

mono vs fluoro

Saltstrong then soaked the mono for 15 minutes and repeated the test with the same result.

Is this test definitive? No, but it’s food for thought, isn’t it?

And don’t take our word for it. Bobby Lane, 2008 Bassmaster Rookie of the Year, Elite Series champion and six-time Bassmaster Classic qualifier, has this to say: “If fluorocarbon has any disadvantages, it's that it sinks and may not be as abrasion-resistant as monofilament. That makes it a poor choice for floating lures. I also tend to use other line types when fishing really heavy cover where I expect my line to get nicked up.”

Deforms under load - The more a material stretches under load, the more “elastic” it is; how easily it then returns to its pre-load length is a question of “plasticity.”

Fluorocarbon is quite elastic, but not very plastic.

After a heavy load, fluorocarbon permanently deforms, retaining the stretch it was forced into to a maximum of about 5 percent.

What We Consider When Choosing The Best Fluorocarbon Fishing Line

When We Like to Use Fluorocarbon as a Main Line

Fluorocarbon has some unique strengths as main line, but it’s not ideal for every situation. As we note above, its true advantage as main line is that it’s quite sensitive, especially when slack, and still as invisible as mono. In short, think of fluoro as a braid replacement.

• When we’re worried about line to leader knot strength - Fluorocarbon leaders have proven their effectiveness, especially as low-visibility shock-absorbers for heavy nylon monofilament But that braid to leader knot is a point of potential failure, and for some anglers, it’s just not worth the risk. In these cases, a fluoro mainline is the way to go.
• When we want slack-line sensitivity - Many pro bass fishermen have adopted fluoro main line for bottom contact techniques like worm fishing. Its high density provides unrivalled slack sensitivity, and you’ll feel bass suck your lure off the bottom more easily. Sensitivity plus low-vis is the winning combination of fluorocarbon, providing the best of mono with the best of braid.
• When we’re fishing water that makes braided superline a no go - As you can tell, we’re not sold on the “invisibility” of fluorocarbon, but there’s no question about how visible braid is by contrast. If using a leader is out, and we need sensitivity in clear water, fluoro is an awesome choice.

How We Use Fluorocarbon Main Line

Fluorocarbon has unique strengths, but it also presents a set of challenging problems as main line. It’s stiff when compared to nylon monofilament or braid, and doesn’t handle or cast well. It knots poorly, too. And when it stretches under load, it can permanently deform, weakening the line further.

What do we do to overcome these weaknesses?

• Re-tie after every fish - After we catch any fish of real size, we like to re-tie our knot. Yes, that’s time consuming, and yes, it’s a pain. But it’s also essential to getting the most from fluoro.
• Strip line - It’s a good idea to be generous with your line and take a conservative approach to abrasion. Strip and re-tie after any contact with rocks, pilings, oyster shells, stumps, etc.
• Use line conditioners - Using products like No products found. will improve the casting of fluorocarbon.
• Loosen your drag a little - Fluorocarbon offers excellent shock strength, but it’s still generally inferior to nylon mono of the same weight. Worse still, its knot strength is much weaker, too. To deal with these issues, we like to run our drag a bit lower than we would with equal-weight mono.

What We Look for in Quality Fluorocarbon

Though only a few companies manufacture the raw materials to make fluorocarbon line, quality varies from brand to brand. Here’s what we look for in a good choice.

• Staying clear - Fluro usually comes from the factory as a clear, transparent monofilament. But poor quality fluoro quickly turns opaque white, and it can even shed a fine powder that coats your gear and hands. We look for fluoro that stays factory-clear during use.
• Knot strength - While definitely not fluoro’s strong suit, some brands are better than others, and a few put most monos to shame! We like to see a well-tied knot hold to at least 60 percent of the line’s tensile strength. Any less, and we’ll pass.
• Abrasion resistance - This, too, is not a particular strength of fluorocarbon, but we look to brands that hold their own for longer than competitors.
• Sensitivity - We’re fishing fluoro for its slack-line sensitivity; if it doesn’t deliver here, we’ll look for a brand that does.
• Smooth casting - While we don’t expect the performance of braid, we’d like to feel that we aren’t struggling. We’ll assess the casting of our favorites, excluding from our reviews any products that just don’t make the cut.

Our Pick - No products found.!

Anglers switch to fluorocarbon when they need the sensitivity of braid in a low-vis situation, especially when they don’t trust leader to mainline knot strength. As a result, good fluorocarbon needs to be sensitive and knot well, since it’s going to be doing the work of both braid and nylon monofilament.

That’s why Seaguar’s Invisx is our top choice. Whatever Seaguar does at their factory is working, and this line exhibits knot strength that makes even mono jealous! It’s just incredible on this front, easily outstripping its competition. It’s also very sensitive and easy to cast, making it an ideal choice for many anglers.

It does have a weakness, however. It’s not terribly abrasion resistant, and if this worries you, P-Line Fluorocarbon or Sunline Super FC Sniper might be better options for you. But if you need very heavy weight fluoro, none of those options can deliver, and here we would turn to the otherwise jack-of-all-trades Vanish for these thicker diameter lines.

Whichever option you choose, if you follow our recommendations, you’ll find that fluoro gets the job done and then some!

Please leave a comment below if you think we’ve missed something in determining the best fluorocarbon line or if our discussion has helped you fish more successfully.