Every few months a redacted document ends up in the news for the wrong reason. Someone drew neat black bars over the sensitive parts, published the file, and a curious reader simply selected the text under the bars and pasted it somewhere else — fully readable. Law firms have done it. Courts and government agencies have done it. It keeps happening because the black bar looks like the job is done.
It usually isn't. In most PDF editors, a black rectangle is just a shape sitting on top of the page. The words underneath are still in the file, untouched. Anyone who opens it can highlight them, copy them, or run a text extractor and read every character you thought you'd hidden.
Why a black box isn't redaction
A PDF keeps text as text — a layer of actual characters positioned on the page — separate from any graphics drawn over it. When you drop a filled rectangle on top, you've added a graphic, but you haven't removed anything. The text layer is still there, sitting quietly beneath the ink. Select-all and copy, or open the file in a different reader, and it comes right back.
Search engines, screen readers, and the little "copy text" feature in every PDF viewer all read that hidden layer. So does anyone who knows to look. The black bar fools the eye, not the file.
What real redaction does
There are two honest ways to make text truly disappear. One is to surgically remove those characters from the file's content — reliable, but fiddly and easy to get wrong. The other is simpler and, for most people, safer: cover the area, then flatten the whole page into an image. Once the page is a picture, there is no text layer left to recover. What you see is genuinely all there is.
This is exactly why our Redact & Sign tool flattens the pages on export. The black boxes are burned into a high-resolution image of the page, and the original text underneath is discarded — not hidden, removed. The trade-off is that the exported text is no longer selectable, which is the correct behaviour for a redaction.
How to redact a PDF, step by step
- Open the Redact & Sign PDF tool and drop your file in. Every page renders in the browser — nothing is uploaded.
- Click Redact, then drag a black box over each piece of sensitive text. Names, account numbers, addresses, signatures — cover them all.
- Switch to Select if you need to nudge or resize a box. Repeat across every page; it's easy to miss one on page four.
- Click Export PDF. The pages are flattened, so the covered text is permanently gone from the file you download.
Then do the thing almost nobody does: open the file you just exported and try to defeat it yourself. Select the text under a bar. Copy it. Search for the name you removed. If nothing comes back, you're done.
Before you share it, check three things people forget
- Metadata. The author name, software, and title fields can carry information you didn't mean to publish. Flattening the visible page doesn't scrub these.
- The file name. "Smith_settlement_confidential.pdf" tells a story before anyone opens it.
- Other copies. The unredacted original is still on your disk and in your email. Redacting one copy doesn't recall the others.