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Co-polymer or Fluorocarbon Leaders?

Published: 12th April 2016 | Author: Simon Robinson

Many anglers will know that there are two main types of tippet for fly fishing; Co-polymer nylon and Fluorocarbon leaders. Fulling Mill ambassador Simon Robinson tells us the difference between the both, and when you should use them depending on what tactic you’re fishing.

Fulling Mill Co-polymer or Fluorocarbon Leaders

“What type of leader material should I fish?” is a regular question these days, with many anglers preferring a certain type of leader over another. In my eyes there isn’t a right or wrong answer, I have come to switching between co-polymer and fluorocarbon depending on the conditions. Both of these tippets have their advantages and I’m a strong believer that anglers should carry both types.

Fulling Mill Co-polymer or Fluorocarbon Leaders

Fluorocarbon Leaders

Fluorocarbon is a relatively modern material in comparison to co-polymer. It was launched as a revolutionary leader material which has a refractive index very close to water. As result, it’s far less visible to the fish – we hope! Since its launch it has become very popular and is now the number one choice for Stillwater anglers particularly when fishing subsurface.  Other properties of fluorocarbon are that is relatively stiff and is also is heavier than traditional leader materials and therefore sinks at a faster rate.

Advantages of using Fluorocarbon

– Low visibility. An advantage in clear water.
– Stiffness. Ideal to use when fishing with long leaders and droppers.
– High Density. Fluorocarbon sinks, it helps keep flies down or your leader subsurface when fishing in calm conditions.
– Long life. Its common knowledge that Fluorocarbon does not decay as quickly as copolymer and is more resistant to UV light – Always dispose of it properly!


– Thicker diameter for given strength.
– Reduced fly movement due to stiffness.
– Fluorocarbon leaders can sink dry flies and pull nymphs too deep if you’re trying to fish high in the water.

Based on these characteristics I use fluorocarbon for most of my stillwater fishing, because;

– I can fish long leaders, particularly with droppers, easily.
– Most stillwaters are extremely clear, so fluorocarbon is great when fishing slow or under an indicator.
– Fishing deep with nymphs on a floating line.
– Large dry flies in calm conditions.

Fulling Mill Co-polymer or Fluorocarbon Leaders

Co-polymer Nylon

Co-polymer is a more traditional leader material, the one the ‘old boys’ use at your local water. Whilst it has been overtaken in recent years by fluorocarbon, there is no doubt that co-polymer still has great advantages in certain situations. Co-polymer is stronger than fluorocarbon for its given diameter and is a lot more supple. This makes co-polymer far more suitable to fishing dries and nymphs close to the surface. It’s also my first choice when fishing fine tippet on rivers where good presentation and natural drifts are essential to catch educated fish.

Advantages of Co-Polymer

– Stronger Breaking strain in finer diameters. This means less breakages when fishing light tippet.
– Increased fly movement due to suppleness. Better presentation and natural drifts on rivers.
– Better dry fly presentation. The fly is not pulled under or drag increased by a leader which has sunk deep.


– Softness of the material can increase tangles.
– Flies and droppers can spin easily.
– Difficult to sink in high breaking strains/diameters.
– Reduced sink rate when wanting to fish nymphs deep with floating line.

Based on these characteristics I use Co-polymer for the following situations;

– Fishing close to the surface with nymphs.
– Dry fly fishing.
– River fishing.
– Fishing light leaders (0.14mm and below)

I would certainly recommend that you carry both Fluorocarbon leaders and Co-polymer. Both have distinct advantages that can make a massive difference on certain fishing days.

As with anything in fly fishing the key is to keep an open mind and react to how the fish are feeding, not how you want to fish. To constantly do this throughout the season I think that you need both leader materials in your tackle box.

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