How to redact a PDF on a Mac, and prove the text is gone
A black box drawn over text is not redaction. How to use Preview's Redact tool, how to check the text is really gone, and what else in a PDF can give you away.
The common mistake is drawing a black rectangle with a shape tool. It looks redacted, and the text underneath can still be selected, searched and copied out.
The free way: Preview's Redact tool
Recent versions of Preview have a real Redact tool. Its own warning says what it does: content marked for redaction is permanently removed when the document is saved and closed. Select the text or area, mark it, and save a copy.
Check it worked
- Open the saved copy, not the one you edited.
- Press Command F and search for a word you redacted. It should not be found.
- Select across the black bar and paste into a note. Nothing from underneath should come out.
What else can give you away
A PDF carries details beyond the page: an author name, the app that made it, sometimes a title. You can see some of them in Terminal:
mdls -name kMDItemAuthors -name kMDItemCreator -name kMDItemTitle file.pdfThe one click way
Simply PDF finds every name, number or email you ask for at once, removes them, clears those hidden details, and checks the saved file for you, then tells you what it found.
Questions
Is drawing a black box over text enough to redact a PDF?
No. The text is still underneath and can be selected and copied. Use a redaction tool that removes the content, then check the saved copy.
Can Preview redact PDFs?
Yes, recent versions of Preview have a Redact tool that permanently removes what you mark when the file is saved. Check the saved copy by searching for a redacted word.