Fishing Rods – The Confusing Difference

The Rod Blank

By Mark Lassagne


Since the beginning of time, anglers have employed some type of rod to entice finned creatures from their watery home. We’ve come along way from the stick and string era to now, when even the savviest angler is confused about what IM rating, guide configuration, grip and reel seats are best for their type of fishing.

Over the next several issues, we will walk you trough an unbiased look at the ever-evolving fishing rod. Starting with the rod itself, the material and the building process, moving into guides and guide configuration, handles and reel seats and then wrapping it up with specific actions that best fit each technique.



Arguably the most important part of a fishing rod is the blank. The blank is the flexible portion between the angler and the lure hopefully with a fish attached. Blanks come in many shapes, sizes and colors, similar to golf clubs they are made with different materials to create a specific action for specific techniques. A few important factor

Cutting the rod pattern

s you will want to know are: the material type, the modulus and weight, then comes the action, power and speed.


A roll of graphite rod material
A roll of graphite rod material


The material used to manufacture fishing rods is called pre-preg. Per-preg, which looks like a thick cloth and consists of resin, scrim plus graphite or fiberglass. Scrim is a very fine (.001”) fiberglass screen that holds the graphite or fiberglass material together, resin a specialized binding agent that when heated bonds the materials together.

There are thousands of combinations of pre-preg where each rod manufacturer configures their own recipe to fit their exact needs of resin, scrim and rod material. The pre-preg arrives to the rod manufacturer in a large roll similar to a large roll of paper you’d see at the craft store. One difference is pre-preg must be stored in the freezer, otherwise the material could start the curing process rendering it useless.


Note: Carbon fiber is graphite



We hear this term often, whether it’s IM6, IM7 or the latest IM9, this one is 60,000,000 modulus or that one is 22,000,000. Does this really matter? What does it mean?

Modulus is a complex measurement describing something’s ability to be temporarily deformed when a force is applied to it. Everything has a modulus, the modulus of a steel rod would be very high where a rubber band is very low.

Besides just a measurement, the modulus gives us an idea of the recovery speed, durability and weight of the blank. In general, a low modulus rod would be more durable and flexible, while a high modulus rod would be stiffer and more sensitive, but not as durable.

Advertised modulus is usually comprised of the base material. This gets tricky as most rods are made up of a blend of different materials rather than just one, so the advertised modulus is that of the main material rather than the combined.

Generally, higher modulus material is more expensive along with being stiffer, thus taking less material to obtain a desired action. The use of less material makes for a lighter rod.

Though modulus is important, it doesn’t mean a low modulus rod will be low priced. There are many reasons for the varied types of materials. Most of the rod value is in the design, build and components, as you will see in this series of articles.



IM6 = 40 million

IM8= 44 million

E Glass = 9 million

S Glass = 12 million



Cutting the rod pattern
Cutting the rod pattern


The building of the rod is relatively simple, once you get the hang of it. As long as you have a few hundred grand in equipment. This is not something you can do at home.

The process starts with a pattern, the pre-preg is rolled out on to a cutting table where it is trimmed to an exact pattern for the desired action. Once cut the material is taken to another special table where pre-preg is rolled into a rod. Using a hot iron, the edge of the pre-preg is attached to a precision ground steel rod called a mandrel. Then, under pressure this special table rolls the material evenly onto the mandrel. The material now has the shape of a fishing rod and is then taken to a machine that spins the rod, wrapping a special cellophane from tip to butt.

Once wrapped, it heads to the oven for several hours of baking at 350° after the baking is complete, the mandrel is removed with a press and then the cellophane is removed. At this point it is possible to use it as a rod; however, most blank builders sand the rough finish and then coat the exterior with a flexible, light urethane finish.



The mandrel is a precision ground steel rod specific to each rod. Every rod has a different mandrel where manufactures may have to have literally thousands on hand.



Rods are finished in an array of colors. They all start out a dark grey to black color. Then, the color is added after the rod has been sanded. Most manufacturers sand the witness marks from the blank, so it’s smooth. From there, it can either be polished or coated. The rod can also remain unfinished without a problem. The resin used in the pre-prig will satisfy as a finish.

A new trend has been to have a finish that looks like a carbon fiber mesh. This is simply a crisscross mesh of graphite added to the outer layer of the rod. The mesh is basically for looks. It may help the rod against being crushed when stepped on, but since the fibers are crossed it doesn’t do much for the action.



The spline of a rod is a slightly thicker area of the rod where the material is overlapped. Since the area is thicker, that portion is slightly stiffer. There are different opinions about using the spline when placing the guides. Since one part of the bank is stiffer, some rod builders say if you don’t use the spline, the rod could roll in your hand under pressure, or may not cast as well. Others say, the difference is so minute that it doesn’t really matter. It could be considered that a rod that is built using the spline would be slightly more contestant than one that doesn’t.



The power of the rod is it’s lifting ability where as a heavy rod could lift more than a lighter rod. These power ratings are generally referred to as: Extra Heavy, Heavy Medium, Medium, Medium Light and Light.



The action is how the rod bends under pressure. A slow action rod will bend in a parabolic shape with the bending focal point near the center of the rod. A fast action will have a focal or bending point closer to the top of the rod. A rod designed for a crankbait would have a slower action where as a rod designed for jig fishing would have a faster action.



The tip is the very top flexible portion of the rod and may also be classified as fast or slow. Though very important, most times the manufacturer build the tip action into the rod, but doesn’t list it separately in the rod action.

Tips are based mostly upon the size of the lure being used and the technique. A rod designed for punching or heavy flipping would have a fast tip. Rods designed to cast a lure would have a slower tip based upon the lure size. If you’ve ever tried to cast a small crankbait with a jig rod you would have a good appreciation for a flexible tip.

We’ve touched on the material, manufacturing process and the basics of rod actions. Coming up, we’ll talk about the guides: micro, titanium, alconite, wire frame, single foot, wrapping, placement and much more.

I’d like to give a special thanks to Wade Cunningham the rod designer at Cousins Rods and Mike Thorson the design engineer at Batson Enterprises for their extensive help with this and future rod articles.

Mark Lassagne is an avid tournament angler and the editor of Bass Angler Magazine.


One thought on “Fishing Rods – The Confusing Difference

  1. Thanks for the comprehensive basics describing the characteristics in rod building. Blank building is now so refined that it almost seems that we’re getting into an area where the electric/reflex field of the fisherman describes the preferred rod blank: HM, IM, SM, GLX, NRX.. ….carbon paper scrim, nano bonding. A rod builder could be a materials scientist. Ok, in building wooden boats epoxy resin is considered better than fiberglass or polyester resin. But fiberglass resin is used in carbon fiber blank rolling, scrim bonding, pressure bonding.. How come epoxy resin is not used as a bonding agent if it’s a better, more expensive glue ?

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