Flexographic printing is a style that uses plates to apply ink to a substrate and is driven by gears to make sure that each plate that is associated with each color is traveling at the exact same rotation in the press. With this style of printing you can print up to 8 colors, made up of 4 color process and 4 spot (PMS) colors or 8 spot colors. The plates are made from your artwork, in the case of spot colors each plate will represent a single color and will be printed on the face/substrate in the exact location that your artwork calls for. If you are printing 4 color process, then 4 plates are made up of Cyan, Yellow, Magenta and Black, then the plates blend the colors together to make the final color you have asked for. The blending process is done by the way the plates are made by mixing dots together.
Flexographic printing is the most cost effective label printing for large runs. These presses can run up to speeds of 300 feet per minute and can hold very tight registration with these speeds. So if you need 50,000 or more labels for any one product your cost to manufacture is going to be less using flexographic printing. You also have the cost of the plates which can run between $60 and $100 per plate. These costs are offset by the lower overall costs of the labels.