Redact, do not cover
A black rectangle placed over text is only a visual cover unless the underlying text is removed. Use a redaction tool that permanently deletes the selected text and image data.
After redaction, try selecting, copying, and searching for the removed words. If the words still appear, the file is not truly redacted.
Remove metadata and comments
Check document properties for author names, software names, company names, titles, and old filenames. Metadata can reveal details that are not visible on the page.
Flatten or remove comments, sticky notes, tracked review marks, and form field defaults when they are not meant for the recipient.
Use passwords carefully
A password can reduce casual access, but it does not fix a file that already contains unnecessary private data. Remove sensitive pages and redacted content before applying a password.
Send passwords through a different channel from the PDF. For example, email the file and share the password through a separate message.
Keep a clean source copy
Save the original in a private folder and create a separate sharing copy. This makes it easier to prove what was sent and avoids accidentally overwriting the only full record.
For public downloads, open the final file in a second PDF viewer and check search, copy, metadata, and page thumbnails before uploading.