Adobe illustrator 10 Manuale Utente

In some cases, the top and bottom objects may have similar color densities so that one 
color is not obviously darker than the other. In this case, the Trap command determines 
the trap based on slight differences in color; if the trap specified by the Trap dialog box is 
not satisfactory, you can use the Reverse Trap option to switch the way in which the Trap 
command traps the two objects.

Light object and dark background: Trap command creates spread. Dark object and light 
background: Trap command creates choke.

1 Select two or more objects, choose Window > Show Pathfinder, and select Trap from 
the palette’s pop-out menu. 

2 In the Thickness text box, enter a stroke width of between 0.01 and 5000 points. Check 
with your print shop to determine what value to use.

3 Enter a value in the Height/Width% text box to specify the trap on horizontal lines as a 
percentage of the trap on vertical lines. 

Specifying different horizontal and vertical trap values lets you compensate for on-press 
irregularities, such as paper stretch. Contact your print shop for help in determining this 
value. The default value of 100% results in the same trap width on horizontal lines and on 
vertical lines. 

To increase the trap thickness on horizontal lines without changing the vertical trap, set 
the Height/Width value to greater than 100%. To decrease the trap thickness on horizontal 
lines without changing the vertical trap, set the Height/Width value to less than 100%.

Height/Width set to 50% and 200%

4 Enter a Tint Reduction value to change the tint of the trap. The default value is 40%.