Anyone responsible for printing goods or packaging knows that some colors, like orange, are just too difficult to reproduce using only CMY inks. A fourth color, black (K, which stands for key color) is often added to subtractive color printing applications. Since C+M+Y actually creates a muddy brownish color due to ink impurities in C, M and Y, adding a true black ink creates the deep color and tones that CMY alone can’t achieve, plus adds density to the shadows. This four-color printin...