Fluorocarbon overview: Sinking and visibility
Fluorocarbon is far heavier than water (SG ≈ 1.78): the only one of the three main lines that truly sinks fast. "Invisible" has no fish-vision study behind it: it just reflects less than nylon.
| Fluorocarbon | Nylon | PE | |
|---|---|---|---|
| Specific gravity (water = 1.00) | 1.78–1.80, sinks fast | 1.13–1.16, sinks slowly | ≈0.97, floats |
| Refractive index (water = 1.33) | 1.42 | 1.52–1.58 | Opaque, not relevant |
| Water uptake | Almost none | Yes; wet properties change | Fibre none; the weave holds water |
| UV resistance | Very good | Degrades | — |
What sinking means on the water
| Technique | Good | Bad |
|---|---|---|
| Jerkbaits, crankbaits | Helps the lure dig; the line does not lift it on the pause | — |
| Bottom work: jigs, Texas rigs | Line lies near the bottom, small bow, clearer bottom feel | — |
| Topwater, floating lures | — | The line pulls the nose down and spoils the action: use nylon |
| Slow-sinking baits, deep water | The bow sinks quickly | Snags structure more |
How invisible is it?
| Claim | Reality |
|---|---|
| Its refractive index is close to water, so it vanishes | It reflects less than nylon; but observers found FC and nylon about equally visible against many backgrounds |
| Fish can't see fluorocarbon | No fish-vision study found; diameter, light, background and angle matter more |
| So use thin fluorocarbon | Diameter is the biggest variable, and FC is not thin for its strength |
Sources: Seaguar technology · VARIVAS line guide · The fluorocarbon myth · Wired2Fish: refraction
← Diameter, strength and abrasion · Colour →
Fluorocarbon overview
Fluorocarbon in six tables: soft vs stiff, main line or leader, diameter and abrasion, sinking and visibility, colour, knots and care.
Related chapters
- Largemouth · Vision — Fluorocarbon: what 'invisible' really buys, and what diameter and stiffness do to bait action
- Line polymer: PE, fluorocarbon, nylon, ester — Fluorocarbon against braid and nylon