The Japanese Mortise Chisel (Tategu) - double layer blade laminated with White Paper steel , has a square cross section that tapers towards the end of the blade. Handles are made from Japanese White Oak. In Japan these are used to make or rework the guides of Japanese sliding doors (shoji) and partition walls.
Start by marking the outer dimensions of the mortise using a square and a pencil.
Next use a mortise guage to mark the width of the mortise.
Using a hammer drive your Japanese mortise chisel into the timber starting near the centre of the mortise at an angle of approximately 45 degrees and keeping within the lines marked by the mortise guage. The mortise chisel needs to be driven in line with the timber for the best end result.
Turn the chisel in the opposite direction to remove your first piece of timber.
The recess is made larger gradually by repeating the first two processes.
When you get to the point where you're almost at the pencil lines use the chisel in a vertical position to remove small shavings until you reach the pencil line. You may need to remove more timber at the bottom of the mortise to allow for the tenon that's going to fit into it.
With the tenon already prepared it's now ready to fit into the mortise.
Tap the tenon into the mortise using a wooden mallet. Now you've got a joint that is strong and suitable for a range of different uses such as tables, chairs and cupboards.