Grip the tool by the midsection, with your forefinger extended for guidance.
The amount of pressure applied should be enough so that the sides of the jointing tool remain in contact with the brick work above and below the horizontal joints, but not so hard that a tramline effect is left behind.
The tramline effect results from using a jointer that has been applied with excess pressure, resulting in the sides of the tool pressing into the mortar instead of against the upper and lower brick.
