How Is Fishing Line Made? Key Facts on Mono, Fluoro and Braid

Fishing line is a vital part of our tackle connecting us to our lures, and hopefully the fish we are seeking to catch. In this article, we explain how fishing …

Fishing line is a vital part of our tackle connecting us to our lures, and hopefully the fish we are seeking to catch.

In this article, we explain how fishing line is made, including information on the main types of fishing line: monofilament fishing line, fluorocarbon fishing line, and braided fishing line (along with fly fishing line).

What Is Fishing Line Made From?

All fishing line is made from various types of polymer or plastic such as nylon (mono lines), polyvinylidene fluoride (fluorocarbon lines), and high molecular weight polyethylene such as Spectra or Dyneema (braided fishing lines).

Fly lines are made with a core of braided nylon or dacron coated with soft polyvinyl chloride (PVC).

How Is Monofilament Fishing Line Made?

Winter Trout Fishing Line Choice
Monofilament fishing line is made by melting and extruding a polymer, then cooling, stretching, and treating it to improve its properties, and finally winding it onto spools for use.

Monofilament fishing line is made by heating pellets of nylon or other similar plastic compounds and extruding the melted nylon through a die so it comes out as single strands of nylon line.

The strands go through a series of rollers that guide them through cooling, stretching, and heating processes until they are the finished article, which is spun onto spools ready for sale.

Monofilament is usually clear, but sometimes a tint is applied for specialty lines for particular applications.

Monofilament fishing line is cheap and supple and offers really good knot strength. It has some stretch built-in, making it more forgiving than fluoro or braided lines.

Monofilament is less dense than water, meaning that unweighted it will float.

Once immersed for a long time, monofilament line will absorb some water. Monofilament fishing lines also degrade in sunlight and should be replaced every year or so if it has been exposed to the elements.

How Is Fluorocarbon Line Made?

Straight fluorocarobon on a baitcaster feature image of a lure and a knot
Fluorocarbon fishing line is produced by polymerizing vinylidene fluoride and other monomers, then melting and extruding the resulting polymer into a continuous filament, which is cooled and stretched to improve its properties and wound onto spools for use.

Fluorocarbon fishing line is made in exactly the same way as monofilament line, except different polymers are used. Fluorocarbon is made using polyvinylidene fluoride (PVDF) as the polymer producing a line that is stiffer and not as supple as monofilament fishing line, but is nearly invisible underwater and has great abrasion resistance.

The refractive index of fluorcarbon line (the degree to which light waves bend or refract as they pass through it) is very close to the refractive index of water (1.3), meaning the line is almost invisible.

Technically speaking, because it is also made as a single strand, fluorocarbon fishing line is a type of monofilament line (albeit it is one made from a different polymer), although in the angling world, because of its different characteristics, it is thought of as a different product.

Fluorocarbon is UV resistant and longer lasting than nylon monofilament lines. It also has greater density and will sink unweighted in water. Fluorocarbon lines have less stretch than monofilament fishing lines meaning it can be easier to detect bites with a braid line and fluorocarbon leader combo than straight mono.

Fluorocarbon is more expensive than monofilament lines but tends to last longer due to its resistance to ultraviolet light degradation. Unlike monofilament lines, fluorocarbon lines do not absorb water.

How Are Braided Fishing Lines Made?

Spinning reels bokeh excellent braid spooled
Braided fishing lines are made by braiding together multiple strands of strong, thin material to form a single, stronger line, which is then wound onto spools for use.

Braided fishing lines are made by taking thin strands of high molecular weight polyethylene (the material used to make milk cartons and plastic shopping bags, but also Kevlar vests) and weaving them together. This is done using special machines that weave the fibers into a braid.

The braided fishing line is then dyed the desired color and undergoes a range of treatments including silicone resin applied to boost its abrasion resistance. Once finished, it is spun onto spools.

Braided lines are usually dyed in one of a number of bright colors. Having the ability to see the braided fishing line helps in detecting bites visually and telling the angler roughly where their bait or lure is in the water column.

Sometimes you’ll see rainbow-colored braided lines in your tackle shop or online store. This is really useful for deepwater jigging or other kinds of deep-sea fishing.

Each color typically runs for 10 yards, so you can count the color changes to work out how much line you have out in the water and therefore calculate the depth you are fishing at!

Braided line offers other advantages too – it is really thin in diameter for a given strength so it is really popular for ultralight fishing as you can cast a long way even when using ultralight lures.

It also has almost no stretch (in contrast to monofilament lines) so you feel every nibble on the lure or bait and when you set the hook it pulls it in hard – handy if your target species have a really bony mouth.

How Is Copolymer Line Made?

Copolymer lines are made from two different nylon polymers with different characteristics, which are melted together and then extruded into a single strand in the same extrusion process as making monofilament line.

Using two different nylon polymers brings a lot of advantages – it is more abrasion resistant and results in a thinner line for a given breaking strain. That means it is less likely to be detected by wary fish and you can fit more line on your reel. There is also less resistance when casting light or ultralight lures.

It also retains the suppleness, and knot strength, of standard monofilament lines but has less stretch. Most anglers find tying knots with this line type similar to modern monofilament fishing lines.

This combination of desirable characteristics makes copolymer a good alternative to either monofilament fishing lines or the more expensive fluorocarbon fishing lines.

How Is Fly Fishing Line Made?

Fly line makers start with the core, which is usually made from strong braided line. Manufacturers tailor the stiffness of the core carefully so the fly line behaves the way it needs to when it is being cast.

The next step in the process is to coat the core made from plastisol resin (the same material used to make soft plastic lures) with various additives including silicone.

The mixture of additives and other materials that are blended with the plastisol differs for different lines and different makers and is what gives the line its special characteristics in terms of polish on the finish, aerodynamic properties, and suppleness, as well as color.

The plastisol is applied to the line in the right proportions to generate the taper. See here for more information on fly line tapers, but essentially most fly lines have a thicker section near the tip that helps anglers to weigh the cast and generate power to punch the line through the air.

The line is cured in an oven once the plastisol mix is applied to the line and then packaged for sale.

Making fly lines is more complex than monofilament lines or fluorocarbon as there are three types: floating fly lines, sinking fly lines, and sink-tip fly lines.

They also come in a range of sizes (or weights), which are paired with rods and reels of a similar “weight” rating.

These range from #1 or #2 (suitable for tiny streams and small fish) right through to #14 (suitable for big powerful fly rods to tackle sailfish, giant trevally, and other powerful saltwater fish).

Combining Different Types of Line

Anglers will sometimes combine different types of lines in one rig to take advantage of their different properties.

For example, because bright-colored braided lines are clearly visible underwater, then you need to add a transparent leader to it to avoid scaring the fish. So monofilament lines and fluorocarbon lines are used as leader material.

Another example is fly lines. Again, because the fly line is opaque, you need to attach a leader made from mono or fluoro line before adding the tippet and the fly. This leader is usually a tapered leader to help the line layout properly when it is cast.


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Rick Wallace is a passionate angler and fly fisher whose work has appeared in fishing publications including FlyLife. He's appeared in fishing movies, founded a successful fishing site and spends every spare moment on the water. He's into kayak fishing, ultralight lure fishing and pretty much any other kind of fishing out there.
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