The earliest fly lines were typically of a fixed length of eight to ten feet and constructed of horsehair. Long strands of horsehair from horse tails were woven to construct a tapered line of typically two strands at the tip and some 40 strands at the butt. Fixed length horsehair lines were the norm well into the 17th century and the hair from a stallion was the preferred material. Until the 19th century, fly lines were being made with woven
silk which replaced horsehair as the material of choice. By the 19th century, fly lines were longer and called running lines that were stored on a fly reel and cast through guides on a fly rod. By the late 19th century, fly lines were still being constructed with silk but were
braided instead of
woven. Braiding created a hollow core which improved flotation.
Nylon, invented by
Dupont and in the 1930s found it way into fly line manufacturing in the late 1940s. Braided Nylon fly lines were cheaper than silk but suffered from their tendency to stretch when wet. In the post-WWII era,
Dacron also known as polyester, became the material of choice for braided fly lines. Braided Dacron fly lines floated well and were lighter, more durable and cheaper to manufacture than silk lines. In 1952, the Cortland Line Company pioneered the use of vinyl to coat braided cores creating the first plastic coated fly lines that are the mainstream today. Throughout the last half of the 20th century, plastic fly line technology facilitated all manner of fly line innovation to address fly fishing for cold-water, warm-water and saltwater species globally. The most recent innovation in fly line materials came in 2007 when
Scientific Anglers introduced
textured fly lines. Texturing the surface of the plastic coated fly lines reduced friction improving casting distance and line pickup.
Fly line buoyancy Fly lines are designed to float (F) or sink (S). Floating lines generally designed with
positive buoyancy for their entire length. Some fly lines have both a sinking section at the tip and a floating running line (F/S). Sinking lines can be fast sinking or slow sinking generally have a specified sink rate in inches per second. Floating fly lines are created by embedding minute air bubbles in the plastic coating around the core. Sinking fly lines or sinking sections of fly lines created by embedding minute particles of tungsten or other heavy metal in the plastic coating. ==Fly line sizes and weights==