Explained
What Is PDF Redaction (and Why Most "Redacted" PDFs Aren't)
A black box on top of text isn't redaction — here's what actually is
5 August 2026 · 5 min read
Quick answer
Real PDF redaction permanently removes the underlying content, not just covers it visually. If you can select or copy text from underneath a black box, it isn't redacted — it's just covered.
It's happened publicly more than once: a government agency or law firm releases a "redacted" document with black boxes over the sensitive parts, and someone discovers the boxes are just shapes — select the text underneath, or delete the shape, and it's fully readable again.
That gap between looking redacted and actually being redacted is the whole subject of this post.
Why a black rectangle usually isn't enough
Most basic PDF annotation tools let you draw a black shape over text as a separate layer sitting on top of the page. Visually it looks redacted. Technically, the original text is still there, underneath, completely intact — selectable, copyable, and extractable by anyone who knows to try.
What real redaction requires
Genuine redaction has to remove the underlying content, not decorate it. The most reliable way to guarantee that: rasterize the page into a flat image with the redaction baked directly into the pixels, then discard the original text layer entirely. Once that's done, there's nothing left to select — the words simply aren't there anymore as text.
iGuardPDF's Redact PDF tool works exactly this way — any page you draw a box on gets fully flattened before the text layer is dropped.
The trade-off: only the redacted pages get flattened
Rasterizing an entire document just to redact one line on one page would make the rest of the document worse — larger file size, no longer selectable text, for no reason. A properly built redaction tool only flattens pages that actually have a redaction on them; every other page stays exactly as it was, still real, selectable text.
How to check if a redaction actually worked
This works on any tool, not just ours: after redacting a document, try to click-and-drag select over the black box in a PDF reader. If any text highlights, the redaction failed — it's decoration, not redaction. This one check takes seconds and catches the exact failure mode that's caused real, public leaks.
Frequently asked questions
Can I redact just part of a page, or does it have to be the whole page?
You draw a box over exactly the area you want gone — as small or as large as needed. The rest of that page (and every other page without a box) stays untouched.
Does redaction remove metadata too?
Redaction as described here covers visible page content. If a document's metadata (author, comments, revision history) also needs scrubbing, that's a separate step worth checking for anything genuinely sensitive.
Is this the same as "blackout" or "censoring" a PDF?
Same idea, different names — the important distinction is always the same one: does it remove the content, or just cover it.
Related tools
Redaction is often part of a bigger document cleanup:
"Redacted" should mean gone, not covered. Before trusting any tool with something genuinely sensitive, run the test: redact it, then try to select the text underneath. If you can read a single character, it isn't redaction.
Ready to redact your PDF properly?
Real flattened black-out, not a shape sitting on top of live text.
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- Every upload and download runs over TLS (HTTPS) — your file never crosses the network unencrypted.
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Full breakdown on our Security page.