And then now another (I hope) helpful tip! A lot of us use aquarium tubing (see the picture!) to prevent the wire from digging into the bark of the tree when we are bending thick branches toward each other with the help of a tension wire between those two branches!
See the example below: Imagine that the right side tubing is bent around a tree trunk or branch! And now we want to bend that left side tubing just like the right side around a trunk or branch, but then we have a problem because we can’t stick the wires through the tube to tighten them together (red arrow)?!
Below: Well here is the solution to that problem! With the help of a concave cutter (see the picture!) cut out a small bite off one side of the tub!
Below: So that you are left with a piece of tube that looks like this (see the picture!)!
Below: Now you do can run both ends of the wire through both ends of the tube en run them through the hole you just cut out! Slide the tube down the wire as tightly against the bark as possible and with a tong twist both ends of the wire as tight as necessary to bend and hold the two branches or two trunks in position!
Hope this will help you!
Cheers,
Hans van Meer.
The Bonsai Blog of Hans van Meer 
hace años que uso este sistema, incluso introduzco dos o tres tubos de acuario uno dentro de otro, cuando la presión del alambre es muy fuerte y la corteza del árbol es fina y sensible. un saludo a todos.
Translation of above comment in English: I have used this system for years, I even insert two or three aquarium tubes one inside the other, when the pressure of the wire is very strong and the bark of the tree is thin and sensitive. greetings to all. Greetings to all.
LikeLike