Lesson #10: Sharpening narrow chisels ...
(a 'tip' from carver Mr. Susumu Ito, passed on here by David Bull)
Carving a traditional Japanese print involves quite a lot of 'picky' delicate work, and many of the tools used are very small indeed. Store-bought 'aisuki' blades go down to about 0.5mm in width, but every carver also has a supply of smaller chisels that he has made himself. Sharpening these tiny chisels can be difficult ...
Each of the chisels and knives has two 'faces' that must be sharpened - the bevelled face, which may be curved (as in the 'aisuki' chisels) or flat (as in the carving knife itself), and then the back side, which must always be absolutely flat. In the case of large, wide chisels, keeping this back surface flat is not difficult, as the fingers can press the chisel down flat while rubbing the tool on the sharpening stone, but there is no room for the fingers to do this in the case of tiny and narrow chisels. It is all too easy to end up with a rounded surface, and a chisel sharpened that way will be difficult to use.
Experienced carver Mr. Susumu Ito was having a look at my chisels one day, and seeing that I must have been having trouble with this, showed me a little 'trick' for keeping the back flat. It involves using a small strip of wood (usually cut from the block currently being carved). Use a 'maru-nomi' (a shallow 'U' shaped chisel) and scoop out a piece about 3 cm long and 1 cm wide - cutting along the grain, not across it. Place this strip crossways on the top surface of the narrow chisel blade (the side with the bevel), and hold it there with a finger.
Now place the flat surface of the blade against the sharpening stone. The strip of wood will extend out to either side of the blade, acting like a pair of canoe 'outriggers' to stop the blade from rocking as you rub the tool over the stone. The back surface of the chisel should thus come out completely flat.
This little trick works very well indeed, and I am grateful to Ito-san for passing it on to me. I'm sure he knows a million more ...