How to redact a PDF properly

Why a black box is not redaction

A PDF usually holds its text as text, with a picture of the page drawn from it. A rectangle drawn on top, a highlight in black, or black text on a black background changes how the page looks. The words are still in the file. Anyone can select the area, copy it and paste it elsewhere, or search the document for the hidden name.

The right way, in any tool

• Use a tool with a real redaction function. Adobe Acrobat Pro has a Redact tool: you mark the areas, then apply the redactions, which removes the content underneath.
• Apply the redactions. Marking is not enough; in most tools the marks are only a preview until you apply and save.
• Remove hidden information too: document properties, comments, attachments and earlier versions stored in the file.
• Save under a new name, and keep the original somewhere the recipient cannot reach.

Check that it worked

• Search the redacted file for the words you removed. There should be no result.
• Press select-all, copy, and paste into a text editor. The hidden words should not appear.
• Check the file properties for the author, the title and the original file name.
• Look at every page, including headers, footers, page numbers in schedules and signature blocks.

Common mistakes

• Redacting the body but leaving the name in a header, a footnote or the file name.
• Redacting in Word and exporting to PDF with tracked changes or comments still inside.
• Sending the wrong file: the original and the redacted copy saved with similar names.
• Redacting a figure but leaving the totals that let a reader work it out.

How Stowbill does it

In a Stowbill data room you draw boxes over what to hide, and the copy that buyers see is rebuilt from images of the pages with the boxes burnt in. There is no text layer left to copy. Your team keeps the original, and if someone uploads a new version, buyers keep seeing the last redacted one until a person redacts it again. Stowbill redacts by hand; it does not find names automatically.

Questions