The debate over nylon monofilament and fluorocarbon leader and tippet material has been alive and well since fluorocarbon was first introduced. There are many advantages and disadvantages of both materials, not the least of which is price. Fluorocarbon is far more expensive than nylon (mono), which is why many anglers prefer to attach pricey fluorocarbon tippet material to more affordable nylon factory tapered leaders.
The result? A cheaper overall leader, with the benefits of fluorocarbon (invisibility, abrasion resistance, higher strength to diameter ratio) at the business end. However, when attaching fluorocarbon tippet to factory tapered nylon factory leaders, we highly recommend – Don’t use a blood knot!
In most cases, fluorocarbon is much harder than nylon. Therefore when attaching fluorocarbon tippet to a nylon leader with a noticeable variation in diameter, fluorocarbon is actually able to cut through the softer nylon material when compressed.. That’s not good.
This is often not noticeable while testing the knot by hand, and might not even manifest itself in many freshwater scenarios, but when targeting hard fighting fish like bonefish, we’ve seen this happen on more than one occasion – Enough times that we’d rather not take the chance.
That said, when using blood knots to attach similar diameter fluorocarbon to hard monofilament (nylon mono that is manufactured to be harder than normal) such as RIO Alloy Hard leader material, we haven’t had any issues. The issue lies when attaching fluorocarbon tippets to factory tapered leaders, which out of necessity to produce, are made from a softer/suppler nylon material.
So, when adding fluorocarbon to your nylon leader, we strongly suggest trying a simple double or triple surgeon’s knot instead. Its easy to tie, believed by many to actually be stronger than a blood knot when connecting lines of differing diameters, and is less likely to cut when under tension.. Give it a try!