Bamboo Fly Rods are generally wrapped with nylon or silk thread. Both work well and produce excellent results if wrapped and finished with care. For those preferring to use silk thread, there are several prominent manufacturers, including YLI, Pearsalls, and Clover Tire.
Brasstown Creek carries only YLI Silk Thread (www.ylicorp.com) and we use that thread to wrap our own bamboo fly rods.
YLI Silk Thread #100 comes in 67 colors, identified at the factory by number, not description (exceptions are White and Black); some retailers attach a color description to a given number, but there is no standard description, and you can’t order from the factory by color, except for White and Black. Brasstown Creek currently carries 26 of these colors, including most of the popular colors for bamboo fly rods.
YLI Corporation has developed an excellent information pamphlet (A Thread of Truth) in the form of a “pdf” file that can be found on their website. This pamphlet is full of great information on thread in general, but does not contain much that is specific to silk thread (see additional information below from the YLI Corporation President). A Thread of Truth has a good section discussing Thread Sizing:
The Cotton Count System (NEc) is the accepted standard for sizing spun threads, and the Denier System (Td) is the accepted standard for sizing filament threads. There is a movement to establish a universal standard (regardless of the thread’s construction), and the TEX system is that standard for industrial sewing thread. There is no standard yet for the home sewing thread market. Note that Tex numbers are grouped over small ranges and each group is assigned a “Tex Number”. See page 8 of A Thread of Truth.
With the NEc (Cotton Count) sizing is based on the number of “hanks” (840 yards) of yarn it takes to equal one pound. Clearly this isn’t a help with silk thread.
Denier count (Td) is used for Continuous Filament Threads. It is the weight in grams per 9,000 meters of the material. YLI Silk Thread #100 is 21d 3×2, and a 21d ply is made up from 7 to 8 individual silk filaments. Thus, YLI Silk Thread #100 has between 42 to 48 filaments of silk in it.
Tex is the weight in grams of 1,000 meters (one Tex = 1gram per 1,000 meters).
So, for fixed weight sizing systems (such as Td and Tex), the higher the number the thicker the yarn. This can be applied to YLI Silk Thread:
Thread Denier Tex No. Tex Size
YLI Silk # 30 567 63 60
YLI Silk # 50 243 27 27
YLI Silk # 100 124 12 12
Note: YLI Silk Thread #100 is six plies of 21d each. So 6 x 21 = 124 denier (closely approximating the 124d shown in the above chart.
I contacted the President of YLI Corporation (based in South Carolina) and he generously provided me with some further information about YLI Silk Thread, much of which I had been unable to obtain elsewhere:
- YLI Silk Thread is made from Filament Silk, essentially long strands of silk as unwound from the cocoon. So the unbroken silk is used as filament silk and the broken strands are chopped up and made into “spun silk”.
- YLI Corporation buys only Japanese silk for their YLI Silk Thread (they have determined it to be of better quality than Chinese or French silk).
- The silk is dyed in skeins in Japan in a small dye house in the mountains overlooking a river that (probably) is full of trout.
- The dyed silk arrives in South Carolina on 200 gram cones (that is about 18,000 yards of thread), and then wound onto the 200 yard spools of #100 YLI Silk Thread. If a large quantity of one color is needed, YLI Corporation can wind the silk onto 1,000 yard spools.