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Knock-out/Overprint
| Allowed and/or strongly encouraged practice |
As said in the previous paragraph, give special care to the knock-out / overprint when you use other colors than RGB or CMYK (for example, a 5th color which could be a spot color, a varnish, a metallic PANTONE®…).
To simplify, there are two methods:
overprint: It means objets are printed one above the other, in the same order they are displayed on the screen.
knock-out: It means, where an object is placed, the other colors are not printed. So there is no overprint.
Here is an example: a text frame is placed above a tint area.
If the text frame is in overprint, here is what we will see when we hide the black coat:
The tint area is not changed : the text frame will be printed over it, which could sometimes cause unintentional transparency effects, like the following one:
Now, here is the case when the text frame is knocked out. Hiding the black coat, the tint area will look like this:
At the intersection of the text frame and the tint area you can see the color has been knocked out, meaning it won’t be printed to prevent any transparency result when printed.
This parameter is essential to create self-sufficient documents when you are using spot colors. You have to choose the best solution to use; we recommend to contact your printer to define the right parameters to apply, depending on the ink and the paper you will use.
| Tip | ||
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Adobe InDesign is configured by default in knock-out. |
Handle the knock-out
for the texts: in your paragraph style, in the section Character Color, you will find two check-boxes to check to command the fill and stroke overprint.
for vectorial frames: the knock-out is handled in the object style, in the sections Fill and Stroke.
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Registration color
| Forbidden practice |
In the swatch palette of any desktop-publishing software you will find the color named Registration. This is a specific color made of:
100% of Cyan
100% of Magenta
100% of Yellow
100% of Black
This swatch is used to trace print and crop marks, displayed on all printer plates.
| Warning | ||
|---|---|---|
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It is strictly forbidden to use this color for any reason. |
Rich Black
| Allowed and/or strongly encouraged practice |
Whatever your layout is, we recommend you to create a rich black swatch: the default black swatch only has 100% of black (no other color), which can cause transparency effects due to overprint.
For the safety of your document and prevent any trouble, we recommend to create a rich black:
either with 60% of Cyan and 30% of Yellow in addition to the 100% of black, if you want a "cold" black (dominance of blue)
or with 60% of Magenta and 30% of Yellow in addition to the 100% of black, if you want a "warm" black (dominance of red)
You will then have a swatch with a powerful ink covering. Such rich black must be reserved for tint areas only. It musn’t be applied on texts, as it could cause registration issues for the printer.
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