What does Redaction mean for your PDF?
Redaction is a deletion, not a decoration. The characters inside the marked area are taken out of the file, and a black rectangle is drawn where they were. Select the area in the saved file and nothing copies, because there is nothing there.
That is what separates it from drawing a filled box over text, which leaves the text object underneath intact and readable by anything that reads the text layer — copy and paste, a search index, a script.
Redaction only deals with what is on the page. Author names, editing dates and other fields live in the file’s metadata and have to be cleared separately.
How do you check that a redaction actually worked?
Open the saved file, not the editor you made it in — editors often show you a preview that hides the difference. Then try, in this order, to read what should be gone.
- Drag-select across the black box and press Ctrl+C (Cmd+C). Paste into a text editor: nothing from under the box should appear.
- Press Ctrl+F (Cmd+F) and search for the name or number you removed. No result.
- Select the whole page with Ctrl+A and paste that. The removed words must not be in the paste.
- Check the document properties: a name in the Author field is not covered by anything you did on the page.
If any of those four turns up the words you covered, the file was annotated rather than redacted and it is still leaking — go back to the original and start again. A file that was redacted properly is also a slightly different size from the original, because characters were taken out of it.