When Black isn’t Black?
When you’re designing for the screen (websites etc), black is black and is pretty straight forward, zero amounts of Red, Green and Blue. There are no hidden pitfalls to catch you out.
When you’re designing for print however, the four colour process (CMYK) is used, where K (key) is the black ink and C is Cyan, M is Magenta and Y Yellow. But, there’s a bit more to it than that!
Selecting Black in Photoshop
The default black in Photoshop isn’t ideal for printing. If you select the black from your colour picker that you normally use, chances are the CMYK values are:- Cyan – 78%, Magenta – 68%, Yellow – 58%, Black – 94%
By using this colour breakdown of black ink, you will encounter the print errors below.
Issue 1, Importing into Adobe InDesign
You’ve created the graphic above in Photoshop using the black as mentioned above and you’re going to place it into your InDesign document on a black background. See below
From Adobe InDesign, you fill the background with the black from the swatch and place the image onto it.
All looks ok, until you see the printed result. What you didn’t expect was that the advert would reproduce as above and 2 shades of black were visible. The reason this has happened is because the default Photoshop black is made up from Cyan – 78%, Magenta – 68%, Yellow – 58%, Black – 94%, whereas Adobe InDesign uses the correct swatch of Cyan – 0%, Magenta – 0%, Yellow – 0%, Black – 100%
Issue Two, total ink coverage is 300%
Export your design as a PDF and use the Adobe Acrobat Output Preview tool to check over the file, if you turn on the Total Area Coverage option it will highlight areas with over ink coverage as a potential over inking problem. For Archant newsprint the maximum ink weight should be 240% TAC, Archant magazine print should be 300% TAC
Issue Three, fine text will become blurry
If you have created text in Photoshop with the default black colour, particularly small type sizes or fine serif fonts, chances are they will reproduce very blurry and possibly missing any fine areas of type.
The reason being, the four sets of ink are being placed over the same area, along with any slight mis-registration causes a loss of detail mostly noticeable on these fine areas. Also, Photoshop rasterises all fonts, basically turning them into soft images, rather than sharp vector graphics.
The solution for the problems above is to not set text in Photoshop and always ensure you select the correct black by entering the appropriate numbers in the Colour Picker. Cyan – 0%, Magenta – 0%, Yellow – 0%, Black – 100%
By entering this combination you are specifying that you only want to use 100% of black and none of the other colour printing plates for this area of colour, resulting in the single pass of ink on this area.
100% Black Not Quite Black Enough?
CMYK black, or the 100K mentioned is great for text, allowing for a crisp and sharp reproduction. On large areas of flat black however, 100K doesn’t really have much impact as black, more as a dark grey, especially when uncoated.
The solution to this is to add a little extra colour to the mix, this is known as creating a Rich Black. The two most common Rich Blacks are those adding Cyan or Magenta.
Rich Cool Black with a cool tint
Cyan – 40%, Magenta – 0%, Yellow – 0%, Black – 100%
Rich Warm Black with a red tint
Cyan – 0%, Magenta – 40%, Yellow – 0%, Black – 100%
Magazine Super Shiner Black (not suitable for small text as fill in is likely, due to dot gain)
Cyan – 50%, Magenta – 50%, Yellow – 25%, Black – 100%
Text set to Knockout
The graphic below illustrates a digital advert that uses white text on a black background. Unfortunately, the black background has been created with all 4 of the process plates (100% Cyan / 100% Magenta / 100% Yellow and 100% K (Black). As white ink is not available, the white text must be set to “Knockout” of the CMYK plates, so that the white newspaper shows through. If the white text is accidentally set to “Overprint” by the designer, the white text will print last. As white ink is not available, any white text set to “overprint”, will disappear from the advert.
The dark background above, was created from (100% Cyan + 100% Magenta + 100% Yellow + 100% K (Black), this would require 400% of ink which greatly exceeds the 240% ink limit (TAC) for porous, newspaper stock. As the newspaper moves over the CMYK plates at 30mph, 10 pages are printed per second, any white text set to knockout will block up and fill in due to the over inked areas and 20% dot gain. To avoid this from happening, we recommend 8pt bold white text knocking out of a single plate black background.