When you need to share a PDF document (such as a bank statement or a medical form) with a third party, it often contains highly sensitive personal information like your Social Security Number or a private account routing number. Your first instinct might be to draw a black box over the text using a basic shapes tool. However, if you simply draw a box over the text and save the PDF, the underlying text data is still perfectly preserved in the file’s code; anyone can easily copy and paste the “hidden” text right out from under your black box. To permanently and securely destroy the sensitive information, you must use the official Redact tool in the macOS Preview application.
How to Use the Redact Tool
The Redact tool in Preview does not just cover the text with a black rectangle; it mathematically deletes the underlying text characters from the document’s binary code, replacing them with a flat, unreadable black image.
- Double-click the sensitive PDF file to open it in Preview.
- Click the Show Markup Toolbar button (the small pencil tip icon) located in the top-right corner.
- On the new toolbar that appears, click the Redact button (it looks like a small black square with a white X inside it).
- A severe warning message will pop up, explicitly stating that redacting content will permanently remove the data and that the action cannot be undone once the document is closed. Click OK to acknowledge the warning.
Your mouse cursor will transform into a crosshair. Simply click and drag your mouse precisely over the specific words, numbers, or paragraphs you wish to hide. As you release the mouse, the text will be instantly replaced by a solid black bar with a subtle “X” pattern inside it.
Verifying the Redaction
Before you email the document to anyone, you must ensure the redaction was successful and the data is truly gone.
First, immediately save the file by pressing Command + S. Then, completely close the Preview application. Re-open the newly saved PDF document. Attempt to click and drag your mouse cursor over the black redacted bar. You will find that it is completely impossible to highlight, select, or copy any text hidden beneath it. The data has been permanently scrubbed from the file.