Rich black, in

printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ...

, is an

ink Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. ...

mixture of solid

black Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''P ...

over one or more of the other

CMYK The CMYK color model (also known as process color, or four color) is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. The abbreviation ''CMYK'' refers ...

colors, resulting in a darker tone than black ink alone generates in a printing process. A typical rich black mixture might be 100% black, 50% of each of the other three inks. Other percentages are used to achieve specific results, for example 100% black with 70%

cyan Cyan () is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK c ...

(C), 35%

magenta Magenta () is a purple-red color. On color wheels of the RGB color model, RGB (additive) and subtractive color, CMY (subtractive) color models, it is located precisely midway between blue and red. It is one of the four colors of ink used in colo ...

(M), and 40%

yellow Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In t ...

(Y) is used to achieve "cool" black. "Warm Black" is 35%C, 60%M, 60%Y, and 100%K. The colored ink under the black ink makes a "richer" result; the additional inks absorb more light, resulting in a closer approximation of true black. While, in theory, an even richer black can be made by using 100% of each of the four inks, in practice, the amount of non-black ink added is limited by the wetness that the

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses, Feces#Other uses, herbivore dung, or other vegetable sources in water. Once the water is dra ...

and printing process can handle. (A safe and practical rule of thumb is that ink coverage should not exceed 240% on normal papers. Papers that "pick", such as low-end recycled papers, should have even less coverage.) Wetness is not a problem with

laser printer Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a Electric charge, negatively charged cylinder call ...

s, however, and registration black (or "400% black") produces very striking results in laser prints. Rich black is often regarded as a color that is "blacker than black". While this is impossible from the point of view of

color theory Color theory, or more specifically traditional color theory, is a historical body of knowledge describing the behavior of colors, namely in color mixing, color contrast effects, color harmony, color schemes and color symbolism. Modern color th ...

, the difference can often be seen in the printed piece. The difference is most apparent in backlit (also known as "translite") pieces, where rich black more thoroughly blocks the light from coming through. The use of rich black has to be based on a full understanding of the printing conditions, including the inks,

printing press A printing press is a mechanical device for applying pressure to an inked surface resting upon a printing, print medium (such as paper or cloth), thereby transferring the ink. It marked a dramatic improvement on earlier printing methods in whi ...

and especially the paper. If too much ink is used on poor quality paper such as

newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has ...

, this may cause the paper to literally fall apart. In addition, excessive amounts of ink may not have a chance to fully dry before the printed result comes into contact with other pages. The additional ink used to create rich black also results in higher printing costs. Care must be taken when using electronic design programs (e.g. when managing a CMYK document in

Adobe Illustrator Adobe Illustrator is a vector graphics editor and Computer-aided design, design software developed and marketed by Adobe Inc., Adobe. Originally designed for the Apple Inc., Apple Mac (computer), Macintosh, development of Adobe Illustrator began ...

or Corel Draw) – "black" may or may not equal 100%K depending on the CMYK profile specified in the image's settings, and Photoshop will represent the various tones using

RGB The RGB color model is an additive color model in which the red, green, and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three ...

values close to black; in an RGB document, "black" always equals RGB value (0, 0, 0). Another reason to use rich black for small areas of black is to avoid

trapping Animal trapping, or simply trapping or ginning, is the use of a device to remotely catch and often kill an animal. Animals may be trapped for a variety of purposes, including for meat, fur trade, fur/feathers, sport hunting, pest control, and w ...

issues. Rich black is often used for text printed over a picture or colored background, because otherwise any slight mis-registration between printing plates would produce a white or colored halo around the text, making it much harder to read.

References

External links

Rich black versus plain black - Printernational
{{Shades of black Shades of gray Graphic design Printing terminology

rich_black Rich black, in printing, is an ink mixture of solid black over one or more of the other CMYK color model, CMYK colors, resulting in a darker tone than black ink alone generates in a printing process. A typical rich black mixture might be 100% b ...