The technique of wiring is fundamental to the art of bonsai, allowing practitioners to shape and guide a tree’s growth into an aesthetically desired form. This process involves wrapping wire around branches and the trunk to hold them in a specific position until the wood has set and can retain the new shape. Selecting the correct materials is crucial, as the wrong wire can damage the bark, impede growth, or fail to hold the position. Choosing the right wire type and thickness is a primary consideration for the health and appearance of the tree.
Selecting the Right Material
The two main types of wire used for bonsai are anodized aluminum and annealed copper, each offering distinct advantages. Anodized aluminum is generally softer and easier to bend, making it a popular choice for beginners and for use on deciduous trees, which have thinner, delicate bark. Aluminum can be applied and adjusted with greater ease, and it is less likely to damage the tree’s surface upon application.
Annealed copper is the preferred choice for more experienced artists, especially when working on conifers like pines and junipers. Copper offers substantially greater holding power for a given diameter compared to aluminum, meaning a thinner gauge can be used to achieve the same result. The annealing process makes the copper soft for application, and it then rapidly “work-hardens” as it is wrapped and bent, creating a strong hold.
Aluminum requires a thicker gauge to match the strength of copper, but the increased surface area of the thicker aluminum can be gentler on the bark of thin-skinned species, such as maples or azaleas. Copper wire is often less visually obtrusive because a thinner wire is used, and it develops a darker patina as it weathers on the tree. However, copper is more difficult to apply, and its rapid work-hardening leaves less room for error or adjustments after the initial wrapping.
Determining the Correct Wire Thickness
Once the material is chosen, selecting the proper gauge, or thickness, is crucial to ensure the wire can hold the branch without causing damage. The general guideline is that the wire should be approximately one-third the thickness of the branch or trunk section being wired. For example, a branch measuring 6 millimeters in diameter would require a 2-millimeter wire.
Using a wire that is too thin will be ineffective, as the branch will simply spring back to its original position or continue to grow past the wire’s resistance. Conversely, an overly thick wire can easily cut into the bark during application or minor adjustments, causing immediate and potentially lasting scars. The goal is to select the smallest gauge that is strong enough to hold the branch in its new position.
For sections requiring greater strength or a more drastic bend, it is better to apply two thinner wires instead of a single thick one. These wires can be twisted together or run parallel along the branch. This technique allows for better flexibility and easier application while distributing the pressure more evenly across the bark. Using multiple wires also allows for more precise control over the shaping process.
Monitoring and Removing the Wire
The final part of the wiring process involves diligent monitoring and timely removal of the wire to prevent permanent scarring, commonly called “wire bite.” Wire must be checked frequently, particularly during the tree’s active growing season in spring and summer, when the trunk and branches rapidly increase in girth. The visual cue for removal is when the wire begins to press noticeably into the bark or when the branch has set in its new position.
The duration the wire remains on the tree varies significantly based on species; fast-growing deciduous trees may only need the wire for two to three months, while slower-growing conifers might require it to remain for a year or longer. When it is time for removal, it is essential to use specialized wire cutters and cut the wire off piece by piece, following the spiral pattern of the wrap. Never attempt to unwind the wire, as this action risks tearing the bark or snapping the branch due to the pressure and twisting force.
Cutting the wire segments individually relieves the tension gradually and prevents the wire from dragging across and damaging the bark as it is removed. If the wire has already started to cut into the bark, it must be removed immediately to allow the tree to heal and minimize the scarring. Careful and timely wire removal completes the shaping process, ensuring the tree retains its artistic form.