There are many grades of bonsai tools. Inexpensive Chinese made tools may need to be sharpened more frequently than harder, higher end Japanese tools. However, with use, all tools eventually need sharpening. Sharpening tools also range in quality. Although some people recommend sharpening your tools with a bench grinder, in most cases, you are better off using a hand-held sharpening stone. Some people use oil stones, but the preferred method of sharpening bonsai tools is a small water stone.
Check the edge of your tool by rubbing your thumb gently and carefully across the edge. If the edge catches the pad of your thumb, your tool may not need sharpening. However, if it does not catch, you should sharpen your tool.
Drop the sharpening stones in water for five to 10 minutes before beginning. This will allow the stones to absorb the water.
Look at the angle of the cutting edge of the blade. You will need to match this angle while honing your bonsai tools.
Rub the stone along the cutting surface of the tool. Make sure the angles of the stone matches the existing angle on the tool. Use the 280-grit stone to remove chips and nicks in the blade. Use the 1500-grit stone to fine sharpen the blade.
Add water to the stone when it starts to dry out. Water acts as a lubricant and cleaner for the stone.