By Julian Adams
Most of my personal bonsai collection is composed of hardy species that grow in temperate climates. Clip and grow techniques are useful in such circumstances but I love the speed and precision with which a branch or trunk can be bent and positioned with wiring techniques. Most techniques have their shortcomings. Wiring is no exception. Left on too long, wire can damage the bark. This is sometimes a severe problem with bark that is very thin or very smooth. The best way to avoid this is to watch closely and remove the wire before the bark is marked. Unfortunately, most of us are not always as attentive as we should be and the wire gets a little too snug. In these circumstances, the damage is often made worse by lack of caution in removing overly snug wire. Figure 1 shows a satsuki azalea limb which has been left wired a bit too long. Careless clipping of the wire for removal created considerable additional damage as shown in figure 2.
Surprisingly, the additional damage was not caused by the wire cutter but by the wire itself. The function of the wire is to move the branch from its natural position to the position chosen by the
bonsai artist. This is accomplished by the stiffness of the wire offsetting the forces in the branch which are trying to return the branch to its original position. The two opposing forces are in equilibrium when the branch is arranged. Over time, the branch submits and hardens to the desired placement. However, the tension in the wire continues to push on the branch until the wire is cut. When the cut is made, the tension is relieved by a sudden small movement of the ends of the wire at the point where the cut is made. Species with fragile bark, such as azaleas and Japanese maples, can be substantially wounded when the sharp ends of the cut wire move. Figure 3 shows the typical movement of the wire ends and the damage beneath.
Damage due to cut end movement during wire removal can be almost entirely eliminated. Use one’s hand to apply slight additional bending force to the limb at the point of cutting. This cancels the tension in the wire so there is no movement of the wire ends when the cut is made. When the hand-generated pressure is released, the wire will move slightly but the movement will be so slow that the bark tearing is avoided. Figure 4 shows another azalea branch which has had the wire left too long. The tension canceling method described above was used when the wire was cut from the limb. Figure 5 shows the indentions made by leaving the wire in place too long but the branch is free of damage from cutting the wire. In this case the indentions will disappear in a year or so and there will be no waiting for damaged bark to heal.