BASALT · JOURNAL
PDF sanitization vs redaction: why you often need both
Redaction and sanitization solve different problems. Redaction removes specific content selected by a reviewer. Sanitization removes classes of active or hidden material that usually should not travel with a release copy. A safe workflow often uses both.
What redaction removes
Redaction targets information on or associated with a page: words, image regions, vector drawings, and sometimes the OCR text beneath a scan. The reviewer decides what must go and why. Correct redaction destroys the underlying object or pixels rather than adding an opaque shape.
Redaction is selective. It should preserve neighboring content and layout, because a disclosure must remain accurate and useful.
What sanitization removes
Sanitization addresses file-level carriers: document information and XMP metadata, comments and annotations, form values, embedded files, JavaScript and actions, hidden layers, stale thumbnails, and earlier incremental revisions. These can disclose information without appearing in the normal page view.
Sanitization is generally class-based: remove all comments, all attachments, or all scripts from the release copy. The exact policy still depends on the purpose; an attachment may be intentional evidence rather than debris.
The safe order
Inspect first so you know what the source contains. Make and review page redactions, apply them destructively, sanitize the output, and write one clean generation. Then reopen the exact candidate with an independent parser and test both dimensions: target content absent and prohibited object classes absent.
If a later operation adds a signature, watermark, Bates stamp, or compression pass, it creates another artifact. Verify again.
A simple failure example
A reviewer removes a client name from every visible page but leaves an attached original spreadsheet and ClientName_Final.xlsx in the embedded-files tree. The redaction can be technically flawless while the release is a complete disclosure failure. Sanitization closes that second channel.
Frequently asked questions
Is “sanitize document” the same as redaction?
No. Sanitization removes hidden or active object classes; redaction selectively removes approved page content. Neither automatically substitutes for the other.
Should every attachment always be removed?
No. Inventory attachments and follow the production instruction. Remove unintended source files; separately review attachments intended for disclosure.
When should verification run?
After the final transformation, against the exact bytes being released. Any later change requires a new verification.
Doing it in Basalt
Basalt combines destructive page redaction with metadata, XMP, annotation, form, attachment, JavaScript, layer, thumbnail, and history removal. Its independent verifier checks the new file before anything is saved. Download Basalt.
Redaction that proves itself
Basalt destroys the content you mark, then re-opens the file it wrote and proves the content is gone before it saves anything. Your documents never leave your Mac.