The short answer
Select all the text on the page and paste it somewhere else. If any redacted words appear, the redaction failed. Then search the file for a known redacted word and check its properties and attachments.
What a failed redaction looks like
Both of these look the same on screen. Only one is actually safe.
Failed: box drawn over text
SSN: 412-55-1234
Pasting returns: SSN: 412-55-1234
Passed: text removed
SSN:
Pasting returns: SSN:
The five checks
Work through them in order. Tick each one as you go.
0 of 5
1. Select all and pasteOpen the file, press Ctrl+A (Cmd+A on Mac) to select everything, copy, and paste into a plain text editor. Look through the pasted text for any word that should have been removed.If it fails: the text is still in the file. The redaction only covered it.
2. Search for a redacted wordUse the find shortcut (Ctrl+F or Cmd+F) and search for a name, number or phrase you know was redacted. Try partial matches too.If it fails: if the viewer finds a match, the text is still searchable.
3. Check the document propertiesOpen the file’s properties or document information. Look at the title, author, subject and keywords for sensitive details.If it fails: clean the metadata before sharing the file.
4. Look for comments and attachmentsOpen the comments or annotations panel and the attachments panel in your PDF viewer. Check each page for hidden notes.If it fails: remove the comments and embedded files, then check again.
5. Test whether pages are imagesTry to select text on a page. If nothing can be selected, the page may be a scan or an image. That is safer for removed text, but scanned pages need a careful visual check.If it fails: if text selects but looks blank on screen, hidden text is present.
Why redactions fail
| Cause | What is left behind |
|---|---|
| Shape or highlight drawn over text | The original text, fully selectable |
| Text colored black or white | The text, only hidden by color |
| Metadata not cleaned | Author, titles, dates and sometimes earlier text |
| Comments, attachments, layers | Content stored outside the page itself |
Questions
Yes. Everything in the five checks uses features found in any PDF viewer and a plain text editor.
Redact it properly the first time.
Airgap Redact removes the text under each box, strips metadata and checks the output before you download it. Free to scan and review.