When we think of colors, we often think of many different shades of each primary color. Take blue for example...it can vary between colors such as baby blue, aqua, turquoise, teal, royal blue, or navy blue.
Many people would assume that the one exception to these color variations is black. After all, we think of black as being absolute darkness, and expect it to appear this way when printed on a document as well. However, black that is used in full-color (process) printing is transparent, like all process inks, and cannot cover ink or paper as thoroughly as you may like.
Although using an opaque black ink may seem like a simple solution, it would cause adverse reactions to other color or high-resolution images that contain black ink. Instead, the wise choice would be to add various "enriched" process blacks to your color menus. Their use should vary according to how and where the black is applied.
Here are two types of enriched blacks to consider using: