Most appropriate method for measuring breaking strain?

kingf000

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I am interested in the claimed very high strength fluoro-coated nylon lines such as Konger, which claims the 7X (0.12mm) has a breaking strain of 5.5lb. I tested this with a pull test by tying line to a pull balance with a clinch knot. It broke just above the knot at 4.5lb, which isn't bad considering what strength you would expect to lose with the knot. But is this the best way to test for breaking strain? It is essentially what Yellowstone use in their pull test. It seems to me that it would relate to the fairly constant pull you get when playing a fish, the sudden stress of the lunges being taken up by the flex of the rod, the drag and the skill of the angler. Others, though, tie the line to a rigid bar and drop a weight. This seems to me to be more of a shock test than a breaking strain measure? Even when retrieving lures with a straight rod, there is always some give in the fly line, the leader and how you are holding the line to reduce the shock. Not surprisingly, lines that have little stretch, such as fluorocarbon or pre-stretched nylon do not come out well in that test - but does it represent anything the line would encounter in use? Would you get a different result if the line were tied to a bar with a give in it to reduce the shock impact?
 

Tangled

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Breaking Strength (tensile strength) is always measured by applying a steadily increasing load to an unknotted line.

The other kind of strength is what I keep banging on about is a function of brittleness - how the material reacts to shock. The drop tests I did show a massive difference between nylon and fluorocarbon and thin diameter (sometimes wrongly called 'pre-stretched) nylon. And I do mean massive - fluoro comes out at almost 5 times weaker.

I think - let's call it shock strength - is really important particularly in low strength lines. People often make the mistake of fishing for largish fish with thin materials and if they also do it with fluorocarbon they're asking to be broken.
 

speytime

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Imo tie it to a hook/eyelet and give a steady pull, in the testing I've done most regular nylon will reach its breaking+ knotted but when I test low diameter I can never ever ever get it to reach its stated breaking strain, drennan ds is my favorite low diameter I can get 90/95% and I can live with that.

Rapala digital scales for testing.

Al
 

williegunn

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That is how I demonstrate that 23.5 breaking strain Seagur breaks around 14lb, a loop at each end, round the door handle and a spring balance and pull till it breaks. 15lb Maxima breaks at about the same.
It may not be scientific but it is a good demo.
 

BobP

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Breaking Strength (tensile strength) is always measured by applying a steadily increasing load to an unknotted line.

The other kind of strength is what I keep banging on about is a function of brittleness - how the material reacts to shock. The drop tests I did show a massive difference between nylon and fluorocarbon and thin diameter (sometimes wrongly called 'pre-stretched) nylon. And I do mean massive - fluoro comes out at almost 5 times weaker.

I think - let's call it shock strength - is really important particularly in low strength lines. People often make the mistake of fishing for largish fish with thin materials and if they also do it with fluorocarbon they're asking to be broken.

According to that I should have been broken when using 8.2lb fluoro just about as soon as the stuff touched the water. Oddly enough it didn't happen and I caught lots of trout - big, hard-fighting ones too - on it. Fish up to 6lb+ that went 50m and more in one gallop.

I used 10lb Seaguar to catch my second steelhead - all 18lbs of it - from the Kispiox River in BC. Same stuff to catch 25 pinks from the Fraser River in just over 2 hours. Not big fish, only 3-6lbs.

fluoro comes out 5 times weaker. Weaker than what? 5 times what? Those statements are meaningless.

I think we are seeing a case of bad workmen blaming their tools, or maybe someone who is so anti-fluoro that his "experiments" are wildly biased.
 

kingf000

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I agree that people using high tech lines are probably using too thin lines. I don't look at it from the point of view of - can my grand max or stroft 4lb line replace my DDS 4lb line. I look at it from the point that my DDS 4lb line is 0.15mm. My grand max at 0.14mm is 4.75lb, stroft at 5lb, so can I get away with those, being slightly thinner, or even the Konger 0.14m at 7.3lb or 0.12mm at 5.5lb? Assuming the given diameters are accurate, which of course they aren't. Even on a single spool, Yellowstone found a big variation in diameter along the length.
 

original cormorant

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The point is that steadily increasing pressure is the only consistent way to test, but everyone knows that isn't the sort of force that will actually cause a failure.
Is there a method for testing "shock" forces which could be applied consistently and become universally recognised?
 

speytime

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That is how I demonstrate that 23.5 breaking strain Seagur breaks around 14lb, a loop at each end, round the door handle and a spring balance and pull till it breaks. 15lb Maxima breaks at about the same.
It may not be scientific but it is a good demo.
All being equal how can anyone dispute that.
With my own experiments I can tell you my door handle had a breaking strain of 8lb ☹️

Al
 

Tangled

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According to that I should have been broken when using 8.2lb fluoro just about as soon as the stuff touched the water.

No Bob, I'd say that you're highly unlikely to be broken on 8.2lb on a stillwater using anything.

Oddly enough it didn't happen and I caught lots of trout - big, hard-fighting ones too - on it. Fish up to 6lb+ that went 50m and more in one gallop.

It's not odd, it's what I'd expect in normal fishing situations.

fluoro comes out 5 times weaker. Weaker than what? 5 times what? Those statements are meaningless.

Let me try to explain it. Breaking Strength (that's the number written on your spool) tells you at what point a line will break with gradually increasing force.

What I'm talking about is Shock Strength and you'll not find that written on your spool. It's how well a line reacts to a sudden sharp application of force. it's a measure of brittleness. It's something you can test easily for yourself.

Results of one test:

"I tested 6lb (0.22mm) Maxima Ultragreen against 6.4lb (0.22mm) Greys Fluorocarbon by hanging 48” lengths of each from my garage ceiling joists and attaching a 1lb weight.

I then dropped the weight fom 47” then inch by inch until the lines broke from the dead drop.

The fluo broke at an average of 3” while the Maxima broke at 14”.

The same test with Sightfree G3 6lb, 0.18mm fluorocarbon broke at 2"

In contrast 6lb 12oz, 0.17mm Reflo Power which advertises itself as resin impregnated mono and is therefore presumably nylon broke at 9”.
(More home-based tests welcome)”

In normal fishing circumstances shock strength does not really come into play, certainly at the higher BSs because of the elasticity in the whole system - leader, line, rod flex, reel drag. But occasionally it does - double hook-up, fish leaping at close quarters, step on your line or wrap it round an oar etc.

It's an effect that is very obvious on low BS leaders - 4lb or less. If you just touch a leaf on a tree you can 'crack-off' a fly just in casting with that stuff.

I think we are seeing a case of bad workmen blaming their tools, or maybe someone who is so anti-fluoro that his "experiments" are wildly biased.

Not by me. Why not try my little test and get back to us, I'd love more data.
 
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Paul_B

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In towden days the rod was a good indicator in what the line strength should be, or what you could get away with and Bayer Perlon was the line of choice.
 

Tangled

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I agree that people using high tech lines are probably using too thin lines. I don't look at it from the point of view of - can my grand max or stroft 4lb line replace my DDS 4lb line. I look at it from the point that my DDS 4lb line is 0.15mm. My grand max at 0.14mm is 4.75lb, stroft at 5lb, so can I get away with those, being slightly thinner, or even the Konger 0.14m at 7.3lb or 0.12mm at 5.5lb? Assuming the given diameters are accurate, which of course they aren't. Even on a single spool, Yellowstone found a big variation in diameter along the length.

That's the best way to use it. I'm pretty sure that all the complaints of unusual breakages are from fishing the stuff too light.
 

williegunn

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I used 10lb Seaguar to catch my second steelhead - all 18lbs of it - from the Kispiox River in BC.

I think we are seeing a case of bad workmen blaming their tools, or maybe someone who is so anti-fluoro that his "experiments" are wildly biased.
Have you still got this Seaguar?
If you have try my experiment, a loop at both ends, one loop round something solid,(better than Speytime's door handle) the other round a spring balance and pull. I would guess 6lb would see it break.
 

kingf000

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According to that I should have been broken when using 8.2lb fluoro just about as soon as the stuff touched the water. Oddly enough it didn't happen and I caught lots of trout - big, hard-fighting ones too - on it. Fish up to 6lb+ that went 50m and more in one gallop.

I used 10lb Seaguar to catch my second steelhead - all 18lbs of it - from the Kispiox River in BC. Same stuff to catch 25 pinks from the Fraser River in just over 2 hours. Not big fish, only 3-6lbs.

fluoro comes out 5 times weaker. Weaker than what? 5 times what? Those statements are meaningless.

I think we are seeing a case of bad workmen blaming their tools, or maybe someone who is so anti-fluoro that his "experiments" are wildly biased.
Anyone comparing nylon and fluorocarbon needs to bear in mind that nylon and nylon copolymer fishing line swells when wet, so becomes thicker and loses around 20% of its strength. So a 5lb line becomes closer to 4lb. Fluorocarbon and coated nylon does not. So any comparative studies need to be done on nylon fishing line that that been soaked in water. Also nylon becomes more brittle in cold weather, as seen by the failure of nylon insulation in the winter. Results from using the dry lines at room temperature are misleading.
Knots also need to be taken into account. The knot used for nylon may not be appropriate for fluorocarbon.
 

glueman

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Anyone comparing nylon and fluorocarbon needs to bear in mind that nylon and nylon copolymer fishing line swells when wet, so becomes thicker and loses around 20% of its strength. So a 5lb line becomes closer to 4lb. Fluorocarbon and coated nylon does not. So any comparative studies need to be done on nylon fishing line that that been soaked in water. Also nylon becomes more brittle in cold weather, as seen by the failure of nylon insulation in the winter. Results from using the dry lines at room temperature are misleading.
Knots also need to be taken into account. The knot used for nylon may not be appropriate for fluorocarbon.
Then take into account the type of nylon
 

Tangled

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Good luck working out what type of nylon any mono uses. And, they're probably all copolymers anyway.
 

speytime

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I've tested nylon (maxima) that's been soaked overnight and it made little to no difference?
But try it for yourself the results aren't unique to me.

Al
 

kingf000

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No Bob, I'd say that you're highly unlikely to be broken on 8.2lb on a stillwater using anything.



It's not odd, it's what I'd expect in normal fishing situations.



Let me try to explain it. Breaking Strength (that's the number written on your spool) tells you at what point a line will break with gradually increasing force.

What I'm talking about is Shock Strength and you'll not find that written on your spool. It's how well a line reacts to a sudden sharp application of force. it's a measure of brittleness. It's something you can test easily for yourself.

Results of one test:

"I tested 6lb (0.22mm) Maxima Ultragreen against 6.4lb (0.22mm) Greys Fluorocarbon by hanging 48” lengths of each from my garage ceiling joists and attaching a 1lb weight.

I then dropped the weight fom 47” then inch by inch until the lines broke from the dead drop.

The fluo broke at an average of 3” while the Maxima broke at 14”.

The same test with Sightfree G3 6lb, 0.18mm fluorocarbon broke at 2"

In contrast 6lb 12oz, 0.17mm Reflo Power which advertises itself as resin impregnated mono and is therefore presumably nylon broke at 9”.
(More home-based tests welcome)”

In normal fishing circumstances shock strength does not really come into play, certainly at the higher BSs because of the elasticity in the whole system - leader, line, rod flex, reel drag. But occasionally it does - double hook-up, fish leaping at close quarters, step on your line or wrap it round an oar etc.

It's an effect that is very obvious on low BS leaders - 4lb or less. If you just touch a leaf on a tree you can 'crack-off' a fly just in casting with that stuff.



Not by me. Why not try my little test and get back to us, I'd love more data.
While painting the bedroom wall I've been thinking about your experiment. As you are using the same force on both lines, you aren't measuring either the breaking strain, relative strength or the stress. I'm sure what you are measuring is the ability for the line to stretch. We already know that nylon stretches more than fluoro, and so, yes, it stretches further before it breaks. You should get the same answer from the stretch test with the balance, in that the nylon line would stretch further before it breaks than the fluoro. To test for stress, you would have to incrementally increase the weight that you are dropping. In practice, it means that, with nylon, the fish will swim further away from you before the line breaks!
 

James9118

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I wrote a series of articles for Sexyloops regarding the strength testing of various materials and knot. I also did an ageing test on nylon that had been left in sunlight for a couple of months.

Firstly, I'll say that if you want accurate data then you need to be using a load frame such as an Instron mechanical tester, fortunately I have access to one of these. Here the material under test is wound onto 'spools' and these are loaded into the machine, thus the testing can be done in the absence of knots. This gets the true tensile strength of the material.

When it comes to knots, there are very, very few in my experience that retain anything like 90% of the materials strength. The exception is the Bimini Twist which retains all the lines strength due to the fact that knot itself twists the line into a multi-strand 'rope' that is stronger than the starting material. A simple knot like a overhand loop (i.e. a 'wind' knot), in contrast loses 30% of the lines strength immediately. From my fairly extensive testing, I think an angler should assume that they've retained 60% of the materials strength once they've finished making up their leader and attached the fly.

What a machine like an Instron produces is a stress/strain response of the material under test. It should be noted that strain is the physics term for stretch. As such, breaking strain is actually the extension at which a material ruptures quoted as a percentage of its starting dimension. This term has been bastardised by anglers to mean tensile strength though. For example, the breaking strain of nylon is typically about 50% (irrespective of diameter), but if you answer the question of 'what breaking strain are you using' with 50%, although technically correct, you'll get a blank stare :)

The stress/strain response gives some interesting information about the material. The area under the stress/strain curve is a measure of the energy required to rupture the material, i.e. the brittleness. This fracture energy/brittleness is important when it comes to shock resistance. At this point I should say that the stress/strain behaviour of most materials is affected by the strain rate. I think in practice we all know this - e.g. if you want to snap a piece of leader it's 'easier' to do so with a sharp jolt rather than a steady pull. Materials with higher fracture energies are more resistant to failing under shock-loading conditions, thus stretchy materials tend to do better in this respect. There is a difference in fracture energy between nylon and flourocarbon, but it's nothing like some of the estimates made in this thread.

Hope this is useful, James.
 
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kingf000

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I've tested nylon (maxima) that's been soaked overnight and it made little to no difference?
But try it for yourself the results aren't unique to me.

Al
So why does everyone else say that the water absorption reduces strength? Did you take the line straight off the spool? If so, then it may still be covered in the lubricant that is used on the die when being manufactured. This would stop the water getting into the nylon, but only for a short time as in use this lubricant would be removed.
 
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