Why Putting a Black Box on Top Is Not Enough: The Right Way to Redact a PDF
Key points
- Know that a black box is only placed on top
- Turn the page into an image to remove the text underneath
- After saving, check that the text cannot be selected
Even if you draw a "black box" over a PDF to hide something, the text underneath may still be there.
Why it remains
In many programs, a black box is just drawn on top of the text. The text data itself is still under the box.
- If you drag over the black area and copy, the text underneath may appear.
- If you open the file in other software and move or delete the box, the text may become visible.
- Searching may find the words you meant to hide.
A reliable way to hide it
Turn the page into an image, so the black box and the page become one picture. Once it is an image, the data for the text underneath is not kept in the file.
Black Out (Redact) Parts of a PDF redacts this way. Redacted pages become images, and their text can no longer be selected or searched.
What about pages you did not redact?
Pages you did not redact stay as they are. Selecting and searching text still work on them.
How to check
- Open the saved PDF.
- Drag to select text over the black area. If you cannot select it, it is not there.
- Search for the words you hid and confirm they are not found.
A box can look black on screen while the content remains. Do not judge by appearance alone.
Use "Black Out (Redact) Parts of a PDF" (free)
Tools that go well with this
- Convert a PDF to Grayscale (Black & White): Turn a color PDF into grayscale or pure black and white, ready for monochrome printing, copying or fax. Choose the resolution.
- Extract or Delete PDF Pages: Keep only the pages you need, or remove the pages you don't.
- Compress PDF: Shrink a PDF to fit under a size you choose, for upload limits.
More guides for this tool
- How to Black Out Part of a PDF (Free, Works on a Phone)
- Information to Hide Before You Submit: When to Consider Redacting a PDF
- How to Check a Redaction Worked: Select, Search and Open in Another App
- Redacting a Scanned or Photographed PDF: When the PDF Is Made of Images
- Redacting the Same Place on Every Page: Headers, Footers and Name Fields
- Checklist Before Sharing a PDF: Redaction, File Name, Pages and Size