|MASTER CLASS IN ROD BUILDING — Building a bamboo fly rod — Part 2 — by Dirk de Villiers
AS I mentioned in the previous article, the best bamboo for fly-rods is Tonkin Cane. Tonkin Cane is used because of its abundance of powerful fibres (known as power fibres) which give the rod its strength and flexibility. A further advantage of Tonkin Cane is the convenient inter-nodal spacing.
It is interesting to note that bamboo is actually a member of the grass family and not a wood.
If you examine bamboo you will find a hard, shiny outer surface called enamel, followed by the densest power fibres. As rod builders we must take great care to not remove any power fibres during the rod building process. As you move towards the inner surface the power fibres become less dense and a soft white material, called pith, becomes more abundant.
Density of power fibres is of paramount importance to rod builders. The densest power fibres are found towards the bottom of the culm and are therefore most suited to butt sections and more powerful rod actions. The top part of the culm is mostly used for building tip sections or butt sections on lighter rods.
A second very important consideration when selecting bamboo is the condition of the enamel and underlying power fibres. Exterior imperfections could be purely cosmetic, such as water marks, or could indicate more serious damage, such as growers’ marks, cut marks, worm holes and leaf nodes. Try to avoid areas with such major imperfections as the integrity of the finished rod could be compromised.
Sometimes the bamboo culm will not be age-cured correctly and will still be a light-green colour. Such culms need to be stored until they are properly dry and are a straw colour. Some bamboo culms may have been straightened by the growers in China and may have surface burn marks. Such sections are not suitable for rod building and should be discarded.
Bamboo culms come in 12 foot lengths and you should ask your supplier to cut these lengths in half to provide you with two 6 foot lengths that are easier to transport and work with. Usually when you buy a bamboo culm, a drying split that runs the length of the culm will be present. If such a drying split is not present, one should be made as soon as possible to prevent random splits occurring during the drying process.
Bamboo in a natural state contains a significant amount of moisture and is not resilient enough to resist taking a set. Heat treatment is required in order to remove excess moisture and improve the rod building qualities of the bamboo.
Heat treatment can become a very technical issue beyond the scope of this article. In my opinion, the best way for the hobbyist to heat-treat bamboo is to flame the culm of bamboo. If you want to end up with a darker toned rod it is best to flame the exterior of the culm. It is also possible to build a light-coloured (also called blonde) rod by splitting the culm in half and flaming the inside surfaces.
Read the full story in the August/September 2014 issue of FLYFISHING.