As a rule, in printing objects that lie on top of one another are left out, meaning that only the visible parts of the objects beneath are printed. This avoids colours mixing and the colour application being too high. However, in some cases it does make sense to apply elements in the layout program in such a way that the bottom elements are overprinted by the top elements. If you want to apply a finish to your print products, for example, when generating the print data you have to make sure that the overprint option is selected for the relevant elements. This also applies if you want to play it safe and make sure that no thin white lines occur around the edges of objects. Black, for example, is set to overprint as standard. You should always activate the overprint preview to see on screen what the result will look like.
Here’s how to apply the correct settings for overprinting in InDesign CC and Illustrator CC:
- To ensure that the maximum colour application is not exceeded, activate the separation preview (Window > Output > Separations Preview) and check the relevant areas by hovering the cursor over them. This will show you the coverage in per cent of the individual colour channels for CMYK, as well as the total of all of them. Make sure that this is not more than the permitted colour application (usually 300%).