Every few months a court filing or a government report makes the news because the blacked-out parts could be copied and pasted straight back out. The black boxes were drawn over the text, and the text was still there.
On screen, covering and removing look identical. In the file they are completely different.
The difference in one sentence
Whiteout (or a black box) covers content. Redaction removes it.
A covering box is one more object drawn on top of the page. Everything underneath is still stored in the PDF and can be recovered by selecting it, copying it, searching for it, or opening the file in another program.
True redaction deletes the text, pictures and drawings in the marked area from the file, then usually draws a box to show that something was taken out.
How to check whether hidden text is really gone
Try these on the finished file, not the one you edited:
- Select across the hidden area and copy. Paste into a plain text editor. If the hidden words appear, they are still there.
- Search the PDF for a word you hid.
- Open it in another reader. Some viewers ignore covering boxes or draw them in a different order.
- Check scanned pages separately. On a scan the words are part of a picture, so searching finds nothing, even when the original picture is still in the file under the box.
What PencoPDF does today
To be exact about the tools on this site:
| Real text under it | Pictures and scans under it | |
|---|---|---|
| White out | Deleted from the file | Covered, not removed |
| Edit a line of text | Old letters deleted | (not applicable) |
| Edit a line on a scan | (not applicable) | Covered by the rebuilt strip, not removed |
| Redact | Deleted from the file | Pixels blanked, removed from the file |
So for a normal PDF made from Word or an online system, whiting out a line or editing it really removes the old words. For a scanned page, or a photograph, whiteout and editing leave the original pixels in the file underneath, even though nobody will see them in a viewer.
The redact tool is the one that removes both: text under its box is deleted, and the pixels of any picture under it, scans included, are blanked, leaving a black box to show where.
What to use for confidential documents
- Use a redaction tool, not a box. On PencoPDF that is Redact a PDF, which removes text and picture content alike. Whiteout also removes text, but not what is in a picture.
- Check the finished file with the copy-and-paste and search tests above before you send it.
- Always check the metadata. The document's title, author and comments can carry the same information you just hid on the page.
- Keep the unredacted original somewhere safe, and send only the checked copy.
The short version
Covering is fine for tidying up a page. For anything that must not be read, the test is not "can I see it?" but "can I copy it back out?"