Fluoro starting to break more often, breaking under rating? 2025
bwjay reply :
I noticed recently that when trying to get snags free, knowing I would probably be breaking line (using my hands to pull, not the rod/reel), that the fluoro side of my double uni leader knot was breaking. In the past, it was the lure/snap that would break off. Not often, considering I rarely snag so bad that I have to break the line, but recently I've been bank fishing and casting in/around trees where my lure gets wrapped around a branch and there's no way I can do anything but break/cut it.
Now, I didn't test the breaking strength when I got the line. I'm using Sunline Sniper FC, 3 months old, 10lb and 14lb, as a leader, paired with 15lb PowerPro and 40lb Super8SlickV2, respectively. I had no issues with breakage before. But now that I've had multiple breakoffs at my leader knot, I'm becoming concerned.
So, today I tested something. I have some 10lb weights that have a hole in the middle, so I have some paracord tied through there with a loop that I can hook onto. I tied a big VMC snap onto one end of the line and put a glove on my hand, wrapped line around it, and gently pulled up. With all knots, I used a Palomar knot, wetted decently with saliva before pulling the snap through the loop, and wetted decently again before pulling tight. Here are the results:
14lb Sniper + 20lb weight: broke before getting the weight into the air, probably 2/3 of the total weight, no surprise
14lb Sniper + 10lb weight: broke before getting the weight into the air, at/inside the Palomar knot
14lb Sniper + 10lb weight: broke before getting the weight into the air, at/inside the Palomar knot again
14lb Sniper + 10lb weight + more saliva and slower/more deliberate knot: got all 10lbs into the air and held it there steady for 20-30 sec, then started pulling up hard on it to add more downward force, caused it to break at/inside the Palomar knot after that
10lb Sniper + 10lb weight: broke before getting the weight into the air, probably 1/2 the total weight. WOW was this upsetting.
I didn't try any more with the 10lb Sniper as I was pretty annoyed at this point. It is possible I would have gotten it into the air but I doubt it.
So, my question is, what's the deal? This fluoro is only 3 months old. It's been kept out of sunlight as much as possible (in a bag 95% of the time). The ONLY thing I can think of, is that, on a canoe trip in June, I had both spools in their plastic boxes inside a canvas(?) pouch on the side of my backpack. This canvas pouch has a zipper and but no ventilation holes. The backpack sat on the floor of the canoe which basically always had a small amount of water in it. My backpack bottom was almost always wet to some degree.
Is it possible that excessive wetness and possibly mild heat (mid-70s) caused the line to weaken significantly? The line was in the plastic box it comes in, so it's not like it was sitting in tons of water, but the pouch it was in was wet a fair amount of time and didn't dry out quickly, so it was probably humid inside the pouch. Could this really cause the line to weaken so significantly?
Needless to say, I feel like I can't trust the line anymore, so I bought some more, and will be keeping it in a hard plastic container away from water, air, and sunlight. But I would still like to know what the heck happened.
WRB reply :
Nearly all fluorocarbon line breaks under 100% knot strength, average is between 75-80%. Compounding the issue is line diameter and both Seaguar and Sunline have smaller diameter per lb test then nearly every other brand.
Dead weight testing varies greatly depending on rate the force is applied, slower applied loads result in higher knot strengths.
If you get 80% knot strength on average with FC line that about all you should expect.
Use premium mono with 100% knot strength, the bass are not line shy.
Tom
islandbass reply :
You have a good mystery on your hands, but I believe in general, that FC is supposed to be good at not absorbing water.
Just my opinion, but I think the line should have broken in your 10# example because a knot was tied. When properly tied, I think the palomar is roughly comes in at 90%. That would suggest to me that it would break when exceeds 9 lbs.
Update: I typed my response before reading WRB's post. I find the 80% knot strength retention surprising to be the expectation.
Finnz922 reply :
possibly old stock. Not old for you, but sat on the shelf or in the warehouse for too long... Over-stretched. once fluoro stretches to a certain point, the next hook set or snag could cause a break.
bwjay reply :
On 7/2/2019 at 7:22 AM, Finnz922 said:possibly old stock. Not old for you, but sat on the shelf or in the warehouse for too long... Over-stretched. once fluoro stretches to a certain point, the next hook set or snag could cause a break.
I thought about that, but I got it from Tackle Warehouse, a pretty high volume seller from my understanding. And this was fresh line off the spool, never stretched.
fin reply :
It might be interesting to test the line itself instead of the knot. Run the line through the hole in the weight and then wrap both ends around the gloved hand.
bwjay reply :
On 7/2/2019 at 7:29 AM, fin said:It might be interesting to test the line itself instead of the knot. Run the line through the hole in the weight and then wrap both ends around the gloved hand.
Just tried this. The 10lb Sniper held up the weight, no problem. I started "bouncing" the weight up and down to put more force on the line, and eventually caused it to snap. This may have partially been due to abrasion, as the weights are coated in a sort of rough texture (but not super rough). I made sure not to rub the line against the weight before lifting it up. So, it seems the line can hold 10lb but because the weight was distributed across multiple points of the line, I don't think it's really the same as something hanging from one end.
Kidflex reply :
Try a different knot than a Palomar. The extreme bends in the knot can cause it to break easy. Try using a cinch type knot. I have less break offs using these type
of knots vs the palomar.
flat reply :
I purchased 3 3000 yard spools of Stren Fluorocarbon many years ago after it was discontinued and it's still going strong. It's been stored in a detached garage that can see 100 to minus 20 temperatures.
Depending on the lures you are using you may consider a thicker fluoro. I've been using 14# braid with a 20# leader for my cranks and topwaters joined with an fg knot. I've ripped my bait out of trees many times, and had I been using an Albright knot I'm sure it would have broken.
WRB reply :
Take a look at at Tackle Tour testing, it coincides with my 25 years of experience with FC line.
Tom
Bluebasser86 reply :
On 7/2/2019 at 10:33 AM, Kidflex said:Try a different knot than a Palomar. The extreme bends in the knot can cause it to break easy. Try using a cinch type knot. I have less break offs using these type
of knots vs the palomar.
Agree with this. I've had better luck with a San Diego Jam for getting the most strength out of my fluoro vs a palomar.
fin reply :
On 7/2/2019 at 10:23 AM, bwjay said:Just tried this. The 10lb Sniper held up the weight, no problem. I started "bouncing" the weight up and down to put more force on the line, and eventually caused it to snap. This may have partially been due to abrasion, as the weights are coated in a sort of rough texture (but not super rough). I made sure not to rub the line against the weight before lifting it up. So, it seems the line can hold 10lb but because the weight was distributed across multiple points of the line, I don't think it's really the same as something hanging from one end.
It's not the same, it's very different. The pressure is distributed across the surface of the thickness of weight (where the line touches the weight), which is much difference than the pressure being focused on one specific point. The smaller that point is, the less weight the line can hold.
But it does show the line might not be defective. When it comes down to it, a different knot is your only option, unless you want to buy some new line. You'll probably never know exactly why the line is breaking. You could buy a new spool to test and compare, and then return it, but even if you learn that the new is better than the old, what good does that do you?
Personally, I gave up on FC and switched to mono.
Try tying a different type of knot on each end of a one foot long piece of line, tying something like a keyring on each end. Use the same thing on each end to make it a fair test. Pull each end and see which knot breaks. Repeat several times, because you might get different results depending on how you tie the knot. I've learned that tiny changes in the way you tie a knot can make all the difference. Changes that you might not even notice you're making. Knot instructions don't always cover all the fine points.
Brad Reid reply :
Jay, I noticed that in your statement of the original problem that it occurred at a Uni junction knot, leader to mainline, and not as it had in the past up at the terminal knot.
What came to mind for me immediately is in a Uni junction knot with its two tied sides, braid cinches down and digs into and holds fluorocarbon very well, so one side of a leader knot is strong. But, the other, the fluorocarbon side of a junction knot, does not bite down into braid. I wonder if that might be the issue?
If you take, for example, an Alberto/Albright sort of junction knot, it is best tied with the fluorocarbon in a loop emulating a hook eye, the braid making the wraps and cinched down and tightly so into the former. If one tied an Alberto/Albright the other way, making a loop with the braid and then wrapping the fluorocarbon around it, the fluoro does a damned poor job preventing the braid from slipping out.
This, no doubt, is an effect related more related to certain sized line pairs and there could be cases where it is less of an issue.
In any circumstance where the fluoro's line diameter is > than the braid, it'd seem to exacerbate the issue.
I'd have to go back to the OP and see if you mention line sizes, whether you might have been tying new sizes together that differed from those used in the past.
No, by the way, to it having anything to do with sunlight or moisture. And, very unlikely it has to do with bad line if you are using a major brand.
Brad
bwjay reply :
Maybe it is just knot strength related. I've been careful to wet my knots to avoid burning the fluoro but it seems that may not be enough. I will see about trying a few different knots that have less bends in them... thanks for the suggestions!
As for line diameter, my 40lb Super8SlickV2 and 14lb Sniper have the same diameter, 0.31mm. I actually didn't plan this but I knew the 14lb would be close; I was gonna go with 14 or 16lb when I bought it and went on the lower side.
Dang it... I was just getting really good at tying the double uni knot. 
Thanks again for everyone's feedback. I do have some fresh line coming from TW so I can run that through the same tests just to see if it responds the same way. I will still pursue other knots to see how they work for my specific lines.
WRB reply :
Before FC line we used 2 knots a version of the clinch knot ( improved or Trilene) and Palomar knot. After FC there are more knots then I can recall trying to solve the issue of poor knot strength......it's the line!
Tom
roadwarrior reply :
Pitzen Knot, Duncan Knot, 16/20... Three names for the knot I use.
NO issues
FishingGeekTX reply :
What Tom said. Sunline is unlike U.S. lines, it is rated closer to break strength, but it's also got a smaller Diameter..so if you buy sunline, you buy much higher #test than you would buying a U.S. line.
Now, after messing up twice, I check diameter vs Stren Original. If it's off, I re-calibrate and/or check interweb to confirm suspicion.
My Defier just came in, it's 17lbs but is a 13lbs Stren Original diameter. My 13lbs defier is like 8lbs test I think, what a waste, should have sent it back. I may still now that I think about it. Same boat as you, you're not alone.
And then Yo-Zuri got me the other way. I thought hey, it's Japanese, 6lbs will be 6lbs. Right? Wrong, it's higher diameter than the 8lbs rating on my BFS ultra-shallow spool and is useless. Ouch!
If fishing line was ruined after some mild heat and water, well...I think the world would catch on pretty quick! 
BassWhole! reply :
On 7/3/2019 at 3:05 AM, roadwarrior said:Pitzen Knot, Duncan Knot, 16/20... Three names for the knot I use.
NO issues
Mono, monofilament, Big Game... Three names for the line I use.
NO issues.
jbrew73 reply :
Were you using a new piece of line for each test? Like finnz started about I think flouro weakens once it has been overloaded. I personally can’t tie a proper Paloma’s knot because it seems I get the line twisted over itself somehow. Looks simple but I literally cannot tie it properly so I use another knot. Uni maybe? Try another knot and see what your results are.
bwjay reply :
On 7/3/2019 at 8:02 AM, jbrew73 said:We’re you using a new piece of line for each test? Like finnz started about I think flouro weakens once it has been overloaded. I personally can’t tie a proper Paloma’s knot because it seems I get the line twisted over itself somehow. Looks simple but I literally cannot tie it properly so I use another knot. Uni maybe? Try another knot and see what your results are.
I was using a new piece of line for each test, absolutely. I made sure there were no stretches or abrasions in each piece before using it. I am definitely going to try other knots though.
Tim Kelly reply :
I've found a san diego jam knot to be a better bet with fluoro. If I want a really strong connection I tie it with a doubled line and only 3 turns, that seems virtually indestructible. Most of the time I just used the single line version with 5 turns and that's plenty strong and quicker to tie.
MittenMouth reply :
I had a bad spool of Sniper FC which cost me quite a bit of money in lures and fish. As a result I switched to Seagur this year and have had a much better experience.
bwjay reply :
Well I just tested the new 14lb and 10lb Sniper and they both broke under the same conditions. The 14lb held the 10lb weight fine until I started pulling up hard on it to simulate more force and it eventually snapped after a couple "bounces". The 10lb could not support the 10lb weight, while pulling up slow. Pretty sad honestly. But at least it's consistent with my line before. It seems my previous line is not defective! At least not compared to other samples of the same line, unless all 4 spools are defective. I'm gonna say this is just how the line is designed. Good to know at the end of the day.
Boomstick reply :
I've been using Berkley Trilene fluorocarbon these days (bogo free at Bass Pro every spring) and have not experienced this problem. I snagged a brand new jig on a branch and given up any hope of retrieving it and I had to wrap the line around my body and play tug-o-war with it to get it to break at the knot. The eye on the jig ultimately ended up breaking and came back with the knot still intact. Now, granted I am sure it was a defective jig, but the amount of force I put on that line was quite impressive!
Should you try Trilene fc, the downside is that it's a stretchier fluorocarbon -- but the strength and knot strength is on par with mono with a 4-6 turn uni knot.
BassThumb reply :
On 7/3/2019 at 5:16 AM, FishingGeekTX said:What Tom said. Sunline is unlike U.S. lines, it is rated closer to break strength, but it's also got a smaller Diameter..so if you buy sunline, you buy much higher #test than you would buying a U.S. line.
That's been my experience with Sunline as well. I always buy lines based on diameter, not rated strength. These ratings seem to be all over the board and rarely are accurate.
On the flip side, take Yo-Zuri Hybrid for example. It breaks at way over the rated strength. It's also much thicker than you'd expect for that strength rating.
I'd be willing to bet that if we took a series of different lines from all over the globe that measured 0.10mm, they'd all break at about the same time under the same load.
bwjay reply :
On 7/13/2019 at 1:33 AM, BassThumb said:That's been my experience with Sunline as well. I always buy lines based on diameter, not rated strength. These ratings seem to be all over the board and rarely are accurate.
On the flip side, take Yo-Zuri Hybrid for example. It breaks at way over the rated strength. It's also much thicker than you'd expect for that strength rating.
I'd be willing to bet that if we took a series of different lines from all over the globe that measured 0.10mm, they'd all break at about the same time under the same load.
I actually just got some 10lb Yo-Zuri Hybrid (wow that stuff is cheap) and tested it the same way I've tested the other lines. It successfully hoisted up the 10lb weight and withstood some light "tugs" to get it to break. Not quite as strong as the 14lb Sniper, but certainly much stronger than the 10lb Sniper. I'll definitely put this stuff to use, maybe as a leader material, maybe on a cheaper spinning reel to let family/friends use. I've read good things and so far at least I know it breaks above its strength rating!
FishingGeekTX reply :
On 7/13/2019 at 1:33 AM, BassThumb said:That's been my experience with Sunline as well. I always buy lines based on diameter, not rated strength. These ratings seem to be all over the board and rarely are accurate.
On the flip side, take Yo-Zuri Hybrid for example. It breaks at way over the rated strength. It's also much thicker than you'd expect for that strength rating.
I'd be willing to bet that if we took a series of different lines from all over the globe that measured 0.10mm, they'd all break at about the same time under the same load.
You just described exactly what i experienced last month.
Bought sunline, realized it was all too low pound test#, had to send it back.
Bought yo-zuri thinking ahah, I need 8lbs diameter so I'll order 8lbs..wrong! It was like original stren..hugely inflated. Had to send that one back too.
And immediately after, I pondered break strength vs line diameter as well
Sunline says 100% nylon. Sure how they cool/extruded matters..but if they are all production fishing lines, can't be that dramatic of a difference, as you say.
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