This is done by passing the blank through a reservoir of paint in one continuous movement to ensure a smoth and complete coat of paint. It is the final alignment of the edges of the carbon cloth and minute variations in the pressure applied by the shrink tape that result in rod sections having a more or less distinct spine ie they are stiffer or more resistant to bending in one plane than another. The relationship of this spine to the rings plays a major role in the casting performance, and thus enjoyment, of a rod. As the design and manufacture of rod blanks advances, the influence of the spine is being reduced and some manufacturers claim to be producing rods with no discernable spine. A ferrule is more than simply a means of joining two or more sections of a rod together.
Ferrules have an important effect on the overall action of a fly rod.
They must be as light as possible for efficient transfer of energy through the rod when casting yet strong enough to withstand maximum rod loading when playing a fish. The best design of ferrule will have the least affect on the action of a rod. Improvements started to be made when the first all-fibreglass ferrule come about. This eliminated the weight of metal ferrules and the hinging effect. All ferrules create some change in a rod's diameter and a badly designed one can break a rod tube from the leverage applied to the inside of the tube.