Why PDF redaction fails — and how to check before you send
Say a paralegal — call him Sam — has to send a court filing with a witness's details blacked out. He draws black rectangles over the names, saves the PDF, and sends it. It looks perfectly redacted. But anyone who selects the text under those boxes, or copies the page into a plain document, gets the names right back.
This is one of the most common — and most damaging — document mistakes there is, and it has embarrassed law firms, companies and governments who thought a black box meant "deleted."
Why the black box isn't enough
In a PDF, a drawn rectangle is just a shape sitting on top of the text. The words underneath are still there, still selectable, still searchable. The same goes for "white-out" text, cropped images that keep their full data, and layers that hide rather than remove. True redaction has to delete the underlying content — and you can't confirm that by looking at the page, because looking is exactly what the box defeats.
Check before it goes out
Open the PDF in scrub. It reads the file on your own device — nothing uploaded — and reports what's actually inside: extractable text, hidden or invisible text, metadata, embedded JavaScript, and data tacked onto the end of the file. If the "redacted" names are still real text in the document, scrub tells you before your recipient finds out.
That verdict is the safety net: it turns "I think it's redacted" into "I checked." To actually remove the content, use your PDF tool's true redaction feature (which deletes, not covers) and then re-check with scrub to confirm it's gone.
The short version
A black box hides text; it rarely deletes it. Never trust a redaction you haven't verified. Get scrub free and check a document before you send it. (Related: check a PDF or Word doc for hidden data.)