Concave cutter
Concave cutter for bonsai are indispensable bonsai tools. It can be used to easily remove both living and dead branches. Bonsai concave pliers are difficult to replace with other tools. The reason lies in the structure of the cutting edges. The concave shaped jaws of concave cutters leave an elongated wound on the bonsai when cutting. This heals very quickly and the scarring is minimal.
Bonsai concave cutter types
Depending on the type, condition and size of the concave cutter, even thick branches can be cut. 3-4cm in diameter are no problem for sharp concave pliers from 27cm in length.
What types of bonsai concave cutter are there ?
- Black: Are the most commonly bought. The black coating is applied before sanding. Black or not says little about the quality of the bonsai concave cutters.
- Stainless steel: Looks classy. But it's not necessarily better than black concave pliers.
- Round: Something between normal concave bonsai cutter with straight cutting edge and knob cutter (round head cutter). The cut when pruning is a little rounder. The round concave pliers cut a little deeper and can withstand significantly more force. That means it can hardly be bent open.
What should be considered when using concave bonsai pliers ?
- Buy the right size. The small concave bonsai pliers under 20cm are only made for very small trees. Most bonsai enthusiasts need concave cutters in the 21-27cm range.
- Always cut lengthways to the trunk or branch with concave cutters, not across. Less sap tracts are injured and the wound then grows together much faster and, above all, better.
- Do not cut branches that are too strong after making a purchase. Especially with the small bonsai pliers, the cutting edges can be bent open with excessive use of force. Try "to get a feel for your concave bonsai cutter". A feeling for which branch is manageable for which concave bonsai pliers.
- A very clean cut is possible with sharp concave cutters. Such wounds on the bonsai grow quickly and well together. With high quality concave pliers, even precise re-cutting is easy.
- We recommend tool oil for the care of the concave bonsai cutter (also for rustproof versions). If they are cleaned and oiled after work, the pliers will run smoothly and there is no risk of rust spots.
What size ?
- under 20cm: These concave cutter are suitable for fine work on a bonsai tree up to 30cm in height
- 20-22cm: Standard concave pliers for cutting bonsai. This can be used to remove branches up to 1.5cm in diameter
- 26-36cm: For bonsai >50cm high. Thicker branches up to 3cm in diameter can be cut
- >36cm: For large garden bonsai, the extra large concave pliers are well suited as an alternative to the saw
You should only buy the small concave bonsai cutter if you want to work on really small trees. The concave bonsai pliers that are most often used have lengths between 21 and 27cm (referred to as medium and large in the shop).
Wound healing
With the correct use of sharp concave cutters, the wounds will heal very well even after removing larger branches. A good example can be seen on the right picture below (left: scars on an elm bonsai (Japanese elm, Ulmus japonica) 3 and 5 years after removal of 3cm thick sacrificial branches, right: wound on a linden bonsai, 2 years after cutting the wound has grown together)
