Vertical paring is necessary when you wish to round off a corner or to make a curve in a piece of wood.
Hold the wood on a bench hook, to protect the surface of the work bench, and support the other end, if necessary, with a timber offcut of the same height as the hook. Hold the chisel upright in both hands with the thumb of the upper hand over the top of the handle to give control and downward force. The lower hand steadies the work and also grips the blade of the chisel between the index finger and the knuckles of the other fingers. Keep your head over the work as you pare away the wood.
Mark the required curve on the wood and cut off the corner, to an angle of about 45 degrees, with a tenon saw. Holding the chisel as described, pare off the corners left by the saw cut. Keep paring off the corners, taking off thin slivers of wood not more than 1mm thick. If you take off thicker cuts than this, the extra effort involved may cause you to lose control of the chisel.
Work as closely in to the curve line as possible, then finish off by smoothing with a file. Find out more about woodworking tools.