CMYK is an acronym for Cyan, Magenta, Yellow, and Key. The “key” color is just an industry term for black. Finally, you have something to talk about with all your offset printing friends!
Four Color Process utilizes only those 4 colors in an overlapping pattern. Each color is printed in a unique halftoned angle to create what is called a Rosette Pattern. This pattern arranges the colors in such a way that it tricks your eye into seeing a full color image, even though there are only 4 colors being printed.
When screen printing an image using CMYK, the old adage of “good, fast, cheap–pick two” comes to mind. Contrary to its wide use in the offset and digital paper printing world, CMYK is not usually the best way to get a high-quality, photo-realistic image printed on a shirt. Yes, it will do the job at a low cost and yes, the color separation process is quicker. However, Simulated Process is a much better option for advanced detail and print quality, especially if you want to print on dark shirts and/or print quality is your utmost concern.
All in all, when it comes to printing photo-realistic images, Four Color Process is a great choice if you want the quickest, most economical option available.