How to check if a PDF is properly redacted
A black bar on the screen doesn't prove anything. Plenty of "redacted" PDFs still have the original text sitting underneath the bar, a click away. These six tests take a couple of minutes and need nothing but a PDF reader.
The 30-second test
- Open the redacted PDF and drag to select across a black bar, including the words on either side.
- Copy (Ctrl+C, or Cmd+C on a Mac) and paste into a blank note.
- If the hidden words appear in the note, the PDF is not redacted. Don't send it.
Why a redaction can look right and still leak
A PDF page can hold several things stacked on top of each other: text, images, drawn shapes, comments and form fields. Most PDF viewers let you draw a black rectangle or a black highlight, and that adds a new shape on top of the page. The text underneath is untouched. It no longer shows on screen, but copy-paste, search, screen readers, other apps and AI tools all read the text, not the picture of it. Court filings and government reports have been "unredacted" this way by people who simply selected the text.
Test 1: copy and paste across the bar
This is the test above, and it catches the most common failure. Select a whole line that runs through the bar and paste it. A properly redacted line pastes with a gap, or doesn't select at all because the page has become an image. If you can't select anything on the page, that's a good sign: there's no text to leak.
Test 2: search for a word you redacted
Press Ctrl+F (Cmd+F on a Mac) and search for a name or number you redacted. Try a few of them, and try part of a number too. Any match means the value is still in the file. Search covers every page, so it also catches a copy you forgot about, such as an account number repeated in a footer on page 9.
Test 3: open it in a different app
Some redaction tools hide content in ways that only their own viewer respects. Open the file in a second program: your web browser (drag the PDF into a Chrome, Edge, Firefox or Safari window), Preview on a Mac, or the Files app on a phone. Then repeat tests 1 and 2. A redaction that survives two different readers is far more likely to be real.
Test 4: check the document properties
The visible page isn't the only place a name can hide. Open the document properties (File > Properties in most PDF readers, or Tools > Show Inspector in Preview) and look at the title, author, subject and keywords. A file exported from Word often carries the author's full name and the original file name, which can be exactly what you were trying to hide.
Test 5: look for comments, attachments and bookmarks
Open the comments or annotations panel, the attachments panel and the bookmarks (outline) panel. Comments can quote the very text that was redacted, attachments can be the unredacted original, and bookmarks often use names or headings from the page. Form fields are another hiding place: a filled-in form can keep its values even when the page is covered.
Test 6: scanned pages and invisible text
A scanned PDF looks like an image, so it's easy to assume there's no text to leak. But many scans have been through OCR (text recognition), which places an invisible layer of text over the picture so the file can be searched. A black box drawn over the image leaves that invisible text in place. Run test 2 on scans too: if search finds a redacted word, the OCR layer is still there.
What a properly redacted PDF looks like
- The words under each bar can't be selected, copied or found by search.
- The document properties don't name the people you redacted.
- There are no comments, attachments or form values that repeat the hidden details.
- Pages you didn't need to change still read normally.
The usual way to get there is to flatten every redacted page, turning it into an image with the bars burned in, so there's simply no text left underneath. In Adobe Acrobat Pro, that means applying the redactions (until they're applied, they're only proposals) and running Sanitize Document to clear hidden data.
How maskyourdocs checks its own work
maskyourdocs flattens every page you mark into an image with the bars burned in, builds a fresh PDF with blank document properties, and drops comments and form annotations from the pages it copies through. Then it reopens the finished file and searches it for every value you marked. If one can still be read on a page that was flattened, it tells you not to send the file. If it still appears on a page you didn't mark, it names the page so you can go back and mark it.
That check can only look for what you marked. It can't know about a name you didn't notice, so the tests above are still worth a minute before anything important goes out.
Questions
How can I tell if a PDF redaction is real?
Select the area under a black bar and copy it, then paste it somewhere. If the hidden words appear, the redaction only covered the text. Also search the PDF for a word you redacted; a proper redaction returns no result.
Can redacted text in a PDF be recovered?
Only if the redaction was done wrongly, for example a black shape drawn on top of text that is still in the file. If the text was removed or the page was flattened to an image, there is nothing left to recover.
Why can I still search a scanned PDF after redacting it?
Many scanned PDFs have been through OCR, which adds an invisible text layer on top of the page image. A box drawn over the image does not remove that layer. The page has to be flattened, or the text removed, for the redaction to hold.
Does maskyourdocs check its own redactions?
Yes. After export it reopens the new PDF and searches it for every value you marked, and warns you if one is still readable on a page you didn't mark. It cannot check for details you never marked, so read the document once yourself.