Photoshop

Adjust overlapping spot colors

To prevent overlapping spot colors from either printing over or knocking out the underlying spot color, remove one of the spot colors where they overlap.

Use a printed sample of the overprinted inks to adjust your screen display to help you predict how colors will look when printed.

Note: In some cases, such as when you use varnish and bump plates, you may want colors to overprint.
  1. In the Channels palette, select the spot channel with the color you want to print.
  2. Choose Select > Load Selection.
    To quickly select an image in a channel, hold down Ctrl (Windows) or Command (Mac OS), and click the channel in the Channels palette.
  3. For Channel, choose the spot channel from step 1, and click OK.
  4. To create a trap when knocking out the underlying color, choose Select > Modify > Expand or Contract, depending on whether the overlapping spot color is darker or lighter than the spot color beneath it. In the Channels palette, select the underlying spot channel that contains the areas you want to knock out. Press Backspace (Windows) or Delete (Mac OS).
    This method can be used to knock out areas from any channels under a spot color, such as the CMYK channels.
  5. If a spot color in one channel overlaps more than one other spot color, repeat this process for each channel that contains the areas you want removed.