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While printing with process colors you have the extra ability to better control the use of black in your designs. By default black overprints, meaning that it is on top of everything and for the most part is unaffected by the elements that surround it. Then again, there is one situation that can destroy its look, and that is when black is on top of two different backgrounds. Especially when one background is white, and the other is an image. What happens is that, since black overprints, it prints on top of white and any other colors, thus creating two distinctly unique values of black. On most designs this would be considered an undesirable effect.
We can fix this situation simply by using a custom Rich Black (also sometimes referred to as Printers Black) color build.
Black crossing over two different backgrounds
Close-up of [Black] value over two different backgrounds.
Black separation deselected to show what will print underneath
Same box with Rich Black applied instead of [Black]
Black separation deselected to show what will print underneath with Rich Black
When reviewing files for press, we always look for black usage. Meaning we check for black usage in boxes, graphic elements, and large text. If the black usage covers two or more backgrounds, we often change the black to a Rich Black or what some call a Printers Black. This is nothing more than a custom build of Black with a little Cyan, Magenta, and Yellow added. Usually K is 100% with smaller equal amounts of CMY. It can really be any amount where the combined CMYK values are less than 250% (i.e., C=50, M=50, Y=50, K=100). Check with your commercial printer for total combined ink amounts over 250% on their presses. Usually it takes longer to dry and can create other ink issues on press. Regardless of values used, we always like to keep the Black at 100%.
If you are intending to make press-ready files, especially for creating press-ready PDF files, then you may want to make the Rich Black yourself. This is often not something that all prepress technicians will do. It is not really a requirement, but in certain circumstances, it can look pretty bad when not addressed. Reviewing black usage is something that we do, and is highly recommend that you consider doing it for yourself.
How to Make a Rich Black Color
QuarkXPress®
To define your own custom Rich Black color build using QuarkXPress®, simply access the Edit Color dialog box and Name: your color build anything you want. For the Model: pop-up menu select CMYK, and make sure the Spot Color checkbox is deselected. Apply the values that you want to use in the fields next to C:, M:, Y:, and K:. Press the OK button to add your color to the Colors palette.
Adobe® InDesign®
To make a custom Rich Black color build, access the New Color Swatch dialog box. Deselect the Name with Color Value checkbox and create a unique Swatch Name:. For the Color Type: pop-up menu select Process and for the Color Mode: pop-up menu select CMYK. Enter the Cyan, Magenta, Yellow, and Black values in the appropriate fields, or use the sliders. Press the OK button when your are finished to add your Rich Black color build to the Swatches palette.
Mircosoft® Office Publisher®
To change your black color to create a rich black, convert your colors to Process colors (CMYK) and select the Custom tab. Apply an equal amount (usually 50 and under) for Cyan:, Magenta:, and Yellow:. Then apply 100 for the Black: value.
See File Considerations for more topics.
Microsoft product screen shot(s) reprinted with permission from Microsoft Corporation.
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