By default, the print modes in the Color Byte RIP are setup to convert any black and/or grey to a process color. To achieve this, all four colors (CMYK) are used to create black and/or grey. Sometimes, converting these to a spot black and/or spot grey is necessary.
What is Process Black? Or rich black as it is sometimes referred to, is an ink mixture of solid black, yellow, magenta and cyan. This typically results in a darker tone than black ink alone generates.
What is Spot Black? Printing using only the black ink and zero percent of yellow, magenta and cyan. This typically results in a lighter tone than process black.