BASALT · JOURNAL
How to combine scanned documents on a Mac
Combining scans is easy until the packet has upside-down pages, repeated cover sheets, inconsistent sizes, no search text, and a file too large to email. The best order of operations prevents doing the same work twice.
Inventory and order first
Rename source files with a stable sequence or arrange them in a manifest. Record page counts and identify duplex scans with blank backs. Remove only pages you have confirmed are truly blank; faint endorsements or handwritten notes can be easy to miss.
Rotate and reorder pages before OCR. Normalizing orientation first improves recognition and avoids a text layer whose coordinates no longer match the displayed page.
Merge, then add navigation
Combine files in the approved order and create a bookmark at each source boundary. Preserve original page sizes unless a filing specification requires normalization; scaling mixed pages can make small text unreadable.
OCR the combined document or its image-only pages to enable search. Check that source boundaries and page counts still match the manifest.
Compress last, with a quality target
Scans dominate file size. Choose a resolution and image quality based on the smallest meaningful text, signatures, and stamps. Never accept a smaller file without visually checking representative pages and fine print. Compressing a large scanned PDF covers the tradeoffs.
If the packet contains sensitive information, redact and sanitize before final compression, then verify the compressed file again because it is a new artifact.
Frequently asked questions
Should I OCR before or after merging?
Either can work, but merging first gives one consistent output and lets you verify a single page sequence. Rotate pages before OCR in either case.
How do I keep track of source boundaries?
Create a bookmark per source file and keep a manifest with source name, page count, and final page range.
Why is the combined PDF enormous?
High-resolution color page images drive size. Compress images only after checking that small text and evidentiary details remain readable.
Doing it in Basalt
Basalt merges end-to-end or interleaved, creates bookmarks per source, rotates and organizes pages, runs local OCR, and compresses with measured output size. All processing remains on the Mac. 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.