Choose New Preset in the panel menu
to create a preset, or double-click a preset to edit it.
In the Trap Width section, for Black, enter a distance
(in points) for how far you want other colors to spread into black,
or for how far you want support screens choked back under black.
Typically, the Black trap width is set to be 1.5 to 2 times the
value of the Default trap width.
For Black Color and Black Density, set values.
Note: To use black trapping features, a color
area must use an ink with a neutral density greater than or equal
to the Black Density, and the ink must occur in percentages greater
than or equal to the Black Color.