How to redact a PDF so the text is really gone
Every few months a court filing or a government report leaks the very names it blacked out, because someone drew black rectangles over the text instead of removing it. Anyone could copy the text from underneath. Real redaction deletes the content from the file. Here's how to do it with tools you probably have, and a thirty-second test that tells you whether it worked.
Updated November 5, 2026 · 3 min read
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Why a black box isn't enough
A PDF stores text and drawings in layers. A rectangle from a drawing or comment tool sits on top of the text, which stays in the file: selectable, searchable and copyable. The same goes for highlighting text in black, or covering it with a white box. A redaction tool is different. It removes what's under the mark, then draws the box to show where something was taken out.
Redact before sending, in SignMaster
If you're redacting because the document is about to go out for signature, such as a contract with an old customer's account number in the example schedule, do it in the same place you send it.
- 1
Upload the PDF to a new envelope
Start a new envelope, upload the PDF, add your signers and go to the Fields step.
- 2
Choose Redact
In the Markup toolbar, pick Redact and drag a box over each part that has to go. You can draw several before committing.
- 3
Apply the redactions
Click the apply button, which counts your boxes (Apply 3 redactions, for example), and confirm with Apply redactions. The content under each box is removed from the document for good, and the whole document is rebuilt as flat page images, so no page keeps selectable text.
- 4
Send as usual
Place the fields and send. SignMaster won't send while a redaction is drawn but not yet applied, so nothing slips out half-finished.
Redact vs White-out
The same toolbar has White-out, which covers an area so you can type a correction on top. It's for fixing a typo, not hiding information. Use Redact for anything that must not be readable.
On a Mac, with Preview
Preview has a redaction tool in its Markup toolbar, built for selecting text. Make a copy of the PDF first with File › Duplicate, open the Markup toolbar, choose the redaction tool and select the text to remove. Apple notes that the redaction becomes permanent once you close the document, and that table of contents entries linking to redacted text aren't removed, so check those by hand.
With Adobe Acrobat Pro
Acrobat Pro's Redact tool lets you mark text, areas or whole pages, then apply all the marks at once. It can also remove hidden information such as metadata, comments and attached files, which a simple redaction leaves behind. The free Acrobat Reader can't redact.
Check that it worked
- Search for it. Open the redacted file and search for a word you removed, such as the surname or the last four digits. No match is what you want.
- Try to copy it. Drag across the black box and paste into a note. If text appears, it wasn't redacted.
- Look past the page. Check the file's properties and any bookmarks or comments for the same information.
- Send the redacted copy, not the original. Rename it with "redacted" in the name so the two never get mixed up.
Questions? Answers.
Can you redact a PDF for free?
Yes. Preview on a Mac includes a redaction tool, and SignMaster's Redact tool is on every plan when you prepare a document to send. The free Adobe Acrobat Reader doesn't redact.
Can redacted text be recovered?
Not if it was truly redacted, because the text is no longer in the file. It can be recovered if someone only drew a box over it, which is why you should test the copy you send.
Is highlighting text in black the same as redacting?
No. A black highlight or a black shape sits on top of the text, and anyone can copy the words underneath. Use a redaction tool that removes the content.
Why can't I select any text in a document I redacted in SignMaster?
Applying a redaction rebuilds the whole document as flat page images, which is what guarantees nothing hidden survives: nothing from the original file is carried over. The file is bigger and its text can't be searched; the signing flow works as before.
Sources
- Apple, Annotate a PDF in Preview on Mac (Markup tools, including redaction) · support.apple.com