What is the difference between overprint and knockout?

Knockout leaves a gap in the colours underneath, so the object prints on clean paper in its own colour. Overprint prints it straight on top, so the inks mix. Almost everything should knock out; small black text is the main exception.

Why did my white text look fine on screen?

Most design programs and PDF viewers don’t show overprint unless you ask them to. Turn on Overprint Preview and you see what the press will do.

Won’t the printer just fix it?

Some printers’ systems ignore overprint on white automatically, many don’t, and most won’t change your file without asking. Sending it right is quicker.

The printer said

“There’s white set to overprint.”

Short answer

Overprint tells the press to print an object on top of the colours underneath instead of cutting them out. White isn’t an ink, it’s bare paper showing through, so a white object set to overprint disappears completely and the background prints straight through it. The fix is to turn overprint off for every white object, so it knocks out, and to check with Overprint Preview before you send the file.

Updated November 3, 2026 · by Azaan Ali, print designer

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Why printers ask for this

By default every object knocks out: the colours behind it are left off the plates, so it prints on clean paper in its own colour. Overprint switches that off for one object. That’s useful for small 100% black text, because it hides any tiny misregistration around the letters, which is why InDesign overprints the [Black] swatch automatically.

The trouble starts when something set to overprint is later changed to white: typically a black logo or line of text, copied from another file, recoloured for a dark background. On screen it still looks white. On the plates there’s nothing there, so it vanishes. Coloured objects set to overprint by mistake have the opposite problem: they mix with what’s underneath, so a yellow shape over blue prints green.

How to find and fix overprint problems

Turn on View → Overprint Preview in Illustrator or InDesign. In Acrobat, open Print Production → Output Preview and tick Simulate Overprinting.
Anything that vanishes or changes colour in the preview is set to overprint. Select it.
Illustrator: Window → Attributes, untick Overprint Fill and Overprint Stroke. InDesign: Window → Output → Attributes, the same two boxes.
Leave overprint on for small 100% black text and thin black lines over colour. Turn it off for large black areas over photos, where the image would show through.
Check placed logos and graphics from other files too: their overprint settings come with them.
In a finished PDF, Acrobat Pro’s Preflight can find white objects set to overprint and fix them.

Or send it to us

Find every object set to overprint, including inside placed logos and PDFs
Set white and light colours to knock out, so they print as designed
Keep overprint where it helps: small black text and fine lines on colour
Send a PDF checked with Overprint Preview, so the proof matches the press

Fix my file · $25 Same day, fixed price, one round of changes included. Or ask a designer first.

Questions

What is the difference between overprint and knockout?: Knockout leaves a gap in the colours underneath, so the object prints on clean paper in its own colour. Overprint prints it straight on top, so the inks mix. Almost everything should knock out; small black text is the main exception.
Why did my white text look fine on screen?: Most design programs and PDF viewers don’t show overprint unless you ask them to. Turn on Overprint Preview and you see what the press will do.
Won’t the printer just fix it?: Some printers’ systems ignore overprint on white automatically, many don’t, and most won’t change your file without asking. Sending it right is quicker.

Terms on this page: Overprint, Knockout, Rich black.

Other things printers say

The printer said“Your black will print grey (or too much ink).”Plain black ink (C0 M0 Y0 K100) prints as a dark grey on large areas; adding some cyan, magenta and yellow under it makes a deep “rich black”, often C60 M40 Y40 K100.The printer said“The transparency needs flattening.”Drop shadows, glows, opacity and blending modes are “live transparency”, which some printers’ systems can’t process reliably.The printer said“There’s no white ink layer.”Printing inks are see-through and CMYK has no white, so on clear film, metallic, kraft or dark stock, colours look faint and anything meant to be white simply isn’t printed.

More on this kind of work: Print file fixing.

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