A black rectangle over text is not yet secure redaction: the text may remain underneath. LibreOffice provides a dedicated redaction workflow with a final export. This guide starts with a text document, spreadsheet or presentation opened in LibreOffice; it does not describe lossless import of arbitrary existing PDFs.
Start with a separate copy
Keep the original protected and work on a copy. Check every page for names, identifiers, images and repeated details in headers or footers. Practise first with invented data. Later redaction cannot undo distribution of an original.
Mark the areas
- Choose Tools, Redact in LibreOffice. The document is transferred to a drawing document in Draw. Compare its page count and appearance with the source.
- Use Rectangle Redaction or Freeform Redaction on the redaction toolbar. Cover the entire confidential area, including characters at its edges.
- Zoom in and inspect coverage. During editing, the shapes are deliberately grey and semitransparent. This working copy is not the release file.
- Check every page, including repeated details, tables and captions. An overlooked copy of a detail remains visible.
Choose the correct export
Explicitly select Redacted Export (Black) or Redacted Export (White). LibreOffice documents that this makes the semitransparent shapes opaque and exports the output as pixels in the PDF. Save with a new, unmistakable name.
Do not confuse this with Direct Export to PDF: the help describes that command as an intermediate copy for review. A saved Draw working file is not automatically the finalized redacted PDF either. Share only the checked final file.
Inspect the saved PDF
Close the output and open that exact file in a separate PDF viewer. Inspect every page at high zoom for visible character fragments and missing or clipped content outside the redaction. Try searching for confidential words and copying text from the affected areas into a local text editor. A failed search alone is not proof of safety, especially with image-based output.
Also inspect the filename, document properties and any attachments for confidential details. Visible redaction as described here is not a blanket promise to sanitize all metadata or extra content. Do not distribute the file while residual data remains unresolved.
Limits and recovery
Pixel-based output may lose searchable text and accessibility; do not assume interactive features or signatures are preserved. Keep the unredacted original protected separately. If anything is wrong, correct the working copy, export again and repeat the checks. Do not merely add another black shape to a defective PDF.