You black-boxed the confidential clauses in a draft and sent it to opposing counsel. Their paralegal copied the 'black box' contents into a Word doc and read everything. Now you're in trouble.
That's the failure mode for fake redaction. Real redaction never lets this happen. Flint does real redaction.
What 'permanent' actually means
A PDF stores text as discrete content streams. A black rectangle drawn on top is a separate overlay — the text streams underneath are untouched. Copy/paste reads the text streams, not the rendering. Permanent redaction means deleting the text streams within the redacted area, then optionally overlaying a black mark for visual indication.
How Flint applies redaction
In redact PDF, you mark regions to redact. When you click 'apply', Flint walks the page content streams, removes any text or image data within marked regions, and writes a black fill in their place. The output has no recoverable text in redacted areas.
Test before sharing
Open your redacted file. Try to select text within a redacted region. If selection returns nothing, redaction is real. If text comes out, redaction failed — usually because a black overlay was used instead of applying redaction. Repeat using Flint's apply-redaction button.
Don't forget non-text content
Embedded images, attached files, comments, and form field values can hide content. Use edit PDF to inspect each. Redact images by marking over them. Remove attachments and comments through the metadata/structure inspector. Form fields require explicit clearing.
FAQ
How do I know redaction was real?
Try to copy text from the redacted area in the saved file. Empty result means real redaction; original text means fake.
Does this work for images?
Yes. Marking over an image region replaces the image data in that area with black.
Can the recipient un-redact?
No — the data is gone. You'd need the original (which you should keep in secure storage) to see the redacted content.
Are there any redaction methods to avoid?
Avoid drawing black rectangles in editors that don't have a dedicated redact function — those rectangles are decoration, not redaction.
Real redaction means the data is gone. Redact permanently.