To remove overprinting: Select the objects, clear the Overprint
Object checkbox on the Trap tab, and then click Apply.
Trapping in color separations
When objects of different colors touch, there is the potential for an
unsightly gap to appear between the colors if the piece isnt printed
precisely aligned, or in register.
Trapping is a technique that purposely distorts the shapes of objects
in color separations where different colors meet. The slight distortion
creates tiny areas called traps where colors overlap. The trap areas
can help avoid the appearance of gaps if the page is printed slightly
out of register.
Before you use trapping in color separations, you should determine
how likely it is that the piece will not be printed in register. You
should consider how beneficial it will be to distort the shape of some
objects to compensate for possible misregistration. For example,
trapping type can ruin the appearance of the text, and probably isnt
necessary.
Trapping choices
Canvas lets you specify two types of trapping, Choke and Spread.
Choke trapping is used to make light background colors trap to dark
foreground objects. Canvas creates a choke trap by slightly reducing,
(choking) the knockout area in the light background object.
For example, if a dark blue A is printed on a pale yellow back-
ground with choke trapping applied to the A, the A remains
exactly the same, but the knockout area in the yellow background
becomes a slightly smaller A shape. The result is that some of the
yellow overlaps the edges of the dark blue A.
Spread trapping is used to make light foreground objects trap into
dark backgrounds. The trap is created by slightly enlarging the fore-
ground object without changing the knockout in the background
color. For example, if a light circle is printed on a dark background
with spread trapping applied to the circle, the circle expands slightly
to overlap, or trap into, the circle knockout in the dark background.
Trapping limitations
Whenever possible, you should design illustrations to avoid certain
trapping problems, and always discuss trapping with your service
bureau and printer to avoid unnecessary expense and inferior results.
Choke trapping reduces the
background knockout slightly
to trap into a dark foreground
object.
Spread trapping enlarges the
stroke of a foreground object
slightly to trap into a dark
background object.