Many of the fishing rods in the old days were made from bamboo or steel, but most of today’s rods are made from graphite, fiberglass or a combination of both materials.
I remember buying a boron bass rod back in the 1980s when boron rods were popular. But boron fibers were extremely stiff and expensive so the amount of boron in so-called boron rods was usually less that 25 percent. Now boron is used merely in the butt end sections of rods and some rod blanks will have a layer of boron with graphite or other materials wrapped around it. The boron adds to the power and strength of the rod, and its stiffness generates a fast recovery from a bend of the rod.
Photo credit to Wagner Rods
Fiberglass Fishing Rods
Fiberglass is highly flexible and heavier than graphite but it is also less sensitive and weaker. Fiberglass rods flex in a parabolic arc so that the entire rod bends from tip to butt when you lift a weight at the end of the line. The distance of the area from the tip of the rod where a rod flexes when loaded determines the action of the rod.
Fiberglass rods are usually slow- or medium-action rods. The slow action of the rod tip gives fish more of an opportunity to get the bait before you pull it away from the fish. Fiberglass rods are ideal for novice anglers because the rods are less expensive and more durable than graphite models.
Graphite is a more sensitive and stiffer material than fiberglass.
Graphite Fishing Rods
Graphite rods are available in different degrees of stiffness referred to as the modulus, a measure of applied stress that it takes to deform or bend a material in its finished process state. The higher the modulus the stiffer the material, which means rod manufacturers can use less material to get the same stiffness.
So a rod with IM8 graphite is lighter in weight than a rod of IM6 graphite, yet both rods will have the same amount of stiffness. The sensitivity of graphite rods allows you to detect strikes easier and the stiffness of the rods produce stronger hook sets. With less flex in the material, graphite rods are rated as fast or extra-fast action.
Composite rods are constructed from fiberglass and graphite or other fibers. The combination of materials makes these rods more sensitive than fiberglass but less powerful than graphite when lifting heavy fish.