Sharp tools are an absolute necessity when cutting or trimming bonsai. Sharp tools will give you clean cuts that are smooth edged so that they will heal over properly.

Wood is a relatively soft material made up of fibers, which are made up of cells. If a cut is not smooth, the cambium will try to heal over but will not be able to do a good job. If the cut does not heal over all the way, the part of the heart wood left exposed will rot. The cut can become a shari if it is in the correct place, or a really bad scar that will not go away.

Remember, some trees look good with a shari and some do not. There must be a good reason for jin and shari, otherwise they will look like a mistake, or artificial. Sometimes shari are made to hide bad cuts, but they must be believable.

The smaller the cut the faster it will heal over. When making a cut with the oval cutter, make it in the same direction as the trunk or branch.

For larger cuts, do not depend on cutters alone for a smooth edge. If you have had the misfortune to make a poor cut, clean it out with a chisel or Dremel tool or die grinder. Remove all the dead wood down to white heart wood and replace it with Durham’s Water Putty, which is commonly available in hardware stores and lumber yards. Fill the hole so that the cambium can roll over and cover the wound.

Another way to be sure the cuts heal over is to cover them with paste. This material will not harden, so it will move as the cut heals over. Snails like this stuff, though, so you must watch for them. If the wound is large I embed small pieces or a coil of #20 copper wire in it.

So, keep the tools sharp and clean. You pay a lot of money for these tools, and they should last a lifetime.

(July 1998)

Tags: John Boyce, tools