BASALT · JOURNAL
Keeping PDFs readable for the long term
PDF is a good archival format, and specific choices within it determine whether a file is still usable much later.
Embed the fonts
A document referencing fonts rather than embedding them depends on those fonts existing on whatever machine opens it. In twenty years that is not a safe assumption, and substitution changes layout and sometimes meaning.
Check with pdffonts. Anything showing no in the embedded column is a future problem.
Avoid encryption for archives
An encrypted document depends on the password surviving as long as the file, which in practice it often does not. Archives outlive the people who created them and the systems that stored the credentials.
If access control is needed, control access to the storage rather than the file.
Keep the text layer
A scanned archive with no OCR is a stack of pictures. It cannot be searched, which for a large archive means it effectively cannot be used.
Run OCR before archiving. It is much easier to do once at ingest than to retrofit across a whole collection later.
Prefer lossless where the content warrants
Compression is a permanent decision. An archive compressed aggressively to save storage cannot be uncompressed later, and storage gets cheaper while the documents do not get any better.
For anything of record, keep the original as received and treat compressed versions as derived copies.
PDF/A, and when it matters
PDF/A is a restricted profile designed for archiving: fonts must be embedded, encryption is not permitted, and external dependencies are disallowed. Many regulatory and court systems require it.
Converting to PDF/A is a specialist operation and most general purpose tools do not do it properly. If a system requires PDF/A, use software that specifically supports it rather than assuming an ordinary export qualifies.
Record what you did
An archive with no record of processing is difficult to rely on later. Note what was OCRed, what was compressed, and what was redacted, because in ten years nobody will remember and the file will not say.
Frequently asked questions
What makes a PDF suitable for long term archiving?
Embedded fonts, no encryption, a text layer if the content is scanned, and minimal lossy compression. Each of those is a choice that determines whether the file is usable decades later.
Should archived PDFs be password protected?
Generally no. The document then depends on the password surviving as long as the file, which archives frequently outlive. Control access to the storage rather than to the file itself.
What is PDF/A?
A restricted PDF profile designed for archiving, requiring embedded fonts, forbidding encryption and disallowing external dependencies. Many regulatory and court systems require it, and converting properly needs software that specifically supports it.
Should I compress documents before archiving?
Keep the original as received and treat compressed versions as derived copies. Compression is permanent, storage gets cheaper over time, and an aggressively compressed archive cannot be restored.
Doing it in Basalt
Basalt is a native macOS PDF toolkit: eighteen tools in one window covering merge, split, page organisation, compression, OCR, passwords, Bates numbering, forms, signing, watermarks and comparison. Every file is processed on your Mac, and the engine that opens documents holds no network entitlement at all, which macOS enforces at the code-signature level. Redaction destroys content rather than covering it, and an independent verifier proves the material is gone before a file is written. A one time $29 licence covers up to three Macs, free for the first 24 hours. basaltformac.com, or brew install --cask chipmunk1101/tap/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.