When building bonsai we often try to create miniatures of full grown trees. Mature trees are often characterized by extreme twists and bends; Branches may turn as much as 180 degrees within a fraction of the branch-length. And although some techniques exist to make strong bends (Think of wrapping branches or trunks with raffia or tape before bending), one cannot make the extreme bends as seen in nature when working on matured trees.
When setting branches in a complex shape, three main limitations play a role: First of all, once branches turn woody, they become brittle, allowing only a certain level of bending before they snap. Secondly, when a branch turns woody, it gets more difficult to bend. This makes it difficult to place bends exactly where one wants, or even to place multiple bends close to one another. Thirdly, when wiring older branches, it takes a long time for them to set in the new shape, which increases the risk of wire marks on the branches and in the bark. These grow out only very slowly. In a tree that is nearing completion you may never be able to get rid of the wire scars.
So. What can one do?
Well.. to be honest.. If you are right now staring at a well-developed tree in a certain style.. Not much. However, if you are in the process of building a tree from scratch, with a lot of the branch-growing still to be done.. Quite a lot! Branches do not start their life as the woody sticks we usually work with. During the first weeks of their lives they get their strength from water pressure in the cells. As the water pressure inside cells (turgor) builds up, the cells get strength of themselves and can keep a young branch up in the air. Only after a few weeks, when the first veins start to grow, and the young branch starts to mature, does wood develop through a process called lignification.
The fact that young branches are not woody yet, gives us the opportunity to work with them and create bends otherwise impossible. Young sprouts easily snap when bend. However, letting the plant dry out a little will reduce water pressure in the cells, making it easier to bend and reducing the risk of snapping. As they will mature within weeks and in this process some cells lignify to wood, they will set quite quickly in the new shape, allowing a quick de-wiring. But also somesome species allow bending of somewhat older branches and trunks in extreme curves. FOr instance pine and juniperus may be bend quite extremely during the first year or so.
Wiring young branches
When working with young branches it is very important to keep in mind that all the strength from the branches comes of water pressure in the cells. Therefor it is very easy to damage the tissue in the branches. So use very thin wire for wiring and apply only light pressure on the wire during application.
As the branches are still very young and do not appreciate a lot of handling, bend the wires. Not the branches. Keep in mind that branches will thicken with time. This will result in a reduction of the wiring effect: Branches tend to even out bends as they thicken. Therefore, make quite extreme bends. You will notice that what looked ridiculously extreme right after applying the wires, within a few years looks quite natural.
After you wire the branches, make sure you water the plant directly. As you work on a plant which is on the dry side and you have just wired young branches, the risk of die-back is very real. Watering is of utmost importance. Furthermore: As the young branches mature, the wires can be removed. Keep in mind that young branches may thicken quickly so check every few days whether the wire is not biting in.