Full color images printed on paper and promotional items use CMYK inks. Often referred to as Process colors, CMYK stands for the Cyan, Magenta, Yellow and Black inks. CMYK inks are transparent and blend to make the wide range of colors needed for full color printing.
While CMYK inks can be used for screen printing, the limitations and challenges that come with textile printing make them a poor choice for most screen printed images. By expanding the color palette to include Red, Green, Blue and Purple, we can make a set of inks that provide good coverage on dark and colored garments, while also allowing for a stable print that is consistent over long print runs. In practice, only the colors needed to reproduce the image are used. This approach is often called Simulated Process, as it expands on the standard process color ink set.
For images using sets of particular colors, or graphics and line work that need colors to be matched, a custom color ink set can be used. Custom colors are mixed from a set of formulas developed by Pantone, and can be specified using a Pantone number. Pantone publishes a set of color books that can be used for selecting and communicating colors. For screen printing we use the Pantone Solid Coated color book.