Part Three: Hollowing, Splitting, Channeling : Page 1 of 2
The techniques described in Part One of this article increase the possibility of bending a thick branch, however, when a branch is so thick or brittle that it can still not be moved into a new position, it’s structure must first be weakened to make its manipulation by coiled or guy wire possible.
Part Three of the series ‘Bending Thick Branches’ addresses the techniques of ‘Hollowing’, ‘Splitting’ and ‘Channeling’.
Hollowing and Channeling involve removal of some of the wood in the centre of the branch that needs to be bent. This can involve removing a channel of wood from along the length of the branch, or the creation a hollow so a sharp bend can be made in a small area of the branch.
The above image shows the branch of a Perovskia atriplicifolia (a rarely used species for bonsai, similar to Lavender or Rosemary). The wood of Perovskia is very brittle; this 1"/2.5cm diameter branch was too straight and was what is termed as an 'eye poker', that is, it grow straight out into the eyes of the viewer!
Before channeling, bending the branch would have been impossible without snapping it. So a deep channel or groove was carved out of the branch to make it much thinner and more pliable. As can be seen, it was then possible to wire and move the channeled branch.
Consideration must be given to the resulting scar. With this particular example, the channel in the branch will not heal over and will always be visible. However, the tree features many shari and jin already and so the channel can be said to complement the overall design. An alternative would of course have been to make the channel underneath the branch so it could not be seen from at least the front view.
The first branch of this Hawthorn required some movement to be added to break up the long, straight section and to bring down the tip of the branch. As a short abrupt bend was required and a long wound (caused by Channeling) needed to be avoided, the branch was hollowed.
(Seen from the reverse side) To hide the resulting wound, the hollow was made at the back of the branch using a Dremel with a small router bit. As much as possible of the interior wood was removed without damaging the cambium layer.
Having finished the hollowing, the branch was easily bent downwards using two guy wires to position the branch precisely.
(Seen from the front view) After the branch had been positioned, the hollow was filled with sphagnum moss and bound tightly with black plastic tape. This will help insulate the wound through the Winter.