For starters, spot colors have to do with offset printing materials, printed in a single run, and is considered any color generated by either pure or mixed ink. The color mode CMYK (Cyan, Magenta, Yellow, Black) is used when printing these colors through offset printing in full-color. These spot colors are widely known for being used to keep the accuracy in a certain color on a printed material during a print run, to provide continuity and match colors as needed. Typically spot colors are used to match up colors on a printed work such as matching text to the background of a logo, or something similar, for example.
In addition, spot colors are used as a way of enhancing the way your work will be printed. As many of us already know, the CMYK color mode can create any and almost all different types of colors, however, when there are large areas of work that must be printed in a specified color, it may come out flawed if you do not utilize a spot color. By using a spot color in a large area, you have a bigger range of control over the accuracy of the color desired.
In order to use spot colors successfully on your printed material, you must first have a printer that contains a special file in addition to the traditional CMYK colors. The spot color while printing is essentially a plate that uses an extra printing unit in order to cover large areas of a specific color shade.
In fact, there are many systems that have been developed with specific predefined colors to be used to match with other (spot) colors. One system was made by Pantone Inc. and is commonly known as “Pantone Matching System” (PMS) and the system has over a 1,000 predfeined colors included in it. The PMS’s predefined colors can also be mixed and blended with their base colors which are also interwoven into their system.
When spot colors are run and developed through the printer to become a physical print, they require you to find the desired color you want from its system and input the specific PMS number for said color. If you are unsure if the spot color will print in the desired color once it’s mixed with the base colors, it is wise to look over a color chart – typically included in these systems (PMS) – before printing.
The link to where I found my information can be located here.