Screened in combination, the four inks of process printing - cyan, magenta, yellow and black - can create the illusion of a wide range of colours. But CMYK cannot reproduce large parts of the visible spectrum, such as very bright colours. After all, these four inks can only reflect light, not emit it.
To get around this limitation, many presses can print additional colours using specially mixed 'spot' inks. One of the most popular choices of spot colour is fluorescent orange (seen on newsstands every day), but you can order just about any mix you like, from metallic finishes to saturated pastels. You can even print using a clear varnish instead of ink, adding lustre to localised areas of the layout.
This project demonstrates how to manage special colours in an Adobe InDesign layout, even when those specials are embedded within placed Illustrator and Photoshop graphics.