Junction Tubing
Junction Tubing was originally used to connect hooks to tubes, and this continues to be the most common use. With the increased use of tubes for fly patterns a variety of Junction Tube materials and applications have developed. In this article I will try to review these.
Junction Tubing can be made of a variety of materials. The four most common materials are Polyurethane (PU), Polyvinyl Chloride (PVC), Rubber, and Silicone.
The flexibility of the tubing can vary significantly depending on the amount of plasticizer that is used. Generally Rubber and Silicone are more flexible and PU is the least flexible. Contrary to this, PU and PVC are extremely durable, and Rubber and Silicone will deteriorate quickly.
In my experience PVC based Junction Tubing is the most versatile. It is very durable, reasonably flexible and inexpensive compared to Silicone and PU.
Junction Tubing usually comes in a variety of diameters in order to accommodate a range of tube diameters. The two most common diameters are approximately 2mm and 3mm. There is also some even larger diameter Junction Tubing for large tubes for big predator patterns. Unfortunately there is no standardization for sizes between tube manufacturers and may cause fitting problems between brands.
Let’s have a closer look at the various ways to use Junction Tubing.
A US tube with a piece of Junction Tubing attached.
The “classic” use of Junction Tubing is to slide it onto a straight piece of US tube or plastic tube. Usually the diameters of those tubes is approximately 3mm. Patterns like the Temple Dog style flies or Willy Gunn type flies are good examples of this. The method is simple and works well. The main disadvantage is that part of the rear of the tube has to be bare so that the Junction Tube can be slid onto it. Cosmetically this shows the Junction Tube edge over the tube, which is not as pleasing as some other methods.
In North America it is common practice to tie on smaller diameter tubes. These are usually 1.8mm plastic tubes. Hooks can be connected by using 2mm Junction Tubes. The disadvantage of the thinner tube is that they can be weak and tend to break under stress.
Here we see an example of a metal tube (Integrated Cone Shrimp Tube), with the 3.2mm Junction Tube attached to the reduce diameter rear aspect of the IC tube. The IC tube is lined with a 1.8mm plastic tube.
A bit more advanced connections are created by metal tubes that have a smaller diameter rear aspect of the tube that allows the tube to be slid on that part and but against the body of the tube. A variety of bottle tubes, bullet tubes and Skittle tubes all have this option. With this configuration the Junction Tube can be tied down when tying the pattern, or left free to slide off the tube.
In order to avoid the edge that can be seen on a straight tube (as discussed in option 1.), there is an option to hide this edge. The way to do this is to leave some 1.8mm tube stick out of a 3mm tube. Slide the Junction Tubing over the 1.8mm tube and let it but up against the 3mm tube. Tie the body over top and there will be no junction visible. This could be called “an integrated Junction Tubing”.
A very simple method that uses no Junction Tubing at all is the free swinging hook method. A small disadvantage of this method is that the loop to up-eye connection tends to hold fish less good than a straight eye to a clinch type knot method.
The hook can also be left “free dangling”. In this case one could simply use a clinch or loop knot and let the hook dangle behind the fly. An improvement on this is to slide a piece of Junction Tubing on the leader and onto the eye of the hook. The Junction tubing will keep the hook tracking straight behind the fly and prevent it from flipping sideways.
Free swinging hook with a straight eye attached via a clinch knot. The junction tubing is slid over the eye and knot to keep the hook trailing in line with the tube.
Those are the main methods of Junction Tube connections that I am aware of. One other aspect to mention here is that it is possible to melt a bump/flange on the plastic tube. This will help to keep the Junction Tube to stay on the tube when a fish is hooked and the hook will slide out of the Junction Tube, instead of the hook coming off the tube together with the Junction Tube. Either way works just fine and it really is just a matter of preference as to which method to use.
