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Fix · a common PDF problem

Black box, but the text still copies?

Short answer. The box was drawn over the text instead of the text being removed. The words are still in the file. Check every page, then redact with a tool that deletes what is under the box.
Redaction checkerRead in this tab
Drop a redacted PDFEach page is rendered here and compared with its text layer.

The checker flags text whose area is almost entirely dark on the rendered page. It cannot see text that exists only as an image.

Results appear here: text hidden under boxes by page, redaction marks that were never applied, and metadata that may name the author.

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Causes and fixes

  1. 1
    Shapes drawn over textDrawing tools and highlighters set to black only cover the words.
    Redact properly
  2. 2
    Redaction marked but not appliedSome editors mark areas first and remove them only when you apply.
    Check for unapplied marks
  3. 3
    Metadata still names peopleThe author or title fields can reveal what the boxes hide.
    Remove metadata

What is going on

A PDF page is built from layers of instructions: draw this text here, draw this image there, fill this rectangle black. A black rectangle placed on top of text changes what you see, but the text instruction is still in the file, so selecting, copying or searching finds it. Anyone who receives the file can read what was meant to be hidden.

The checker above renders each page and compares it with the page’s text layer. Where text sits in an area that renders almost entirely dark, it reports the page and the first characters, without printing the full hidden text. It also reports redaction marks that were placed but never applied, and metadata such as the author’s name.

A real redaction removes the content. The redaction tool here rebuilds each page that has a box as an image with the box burned in, drops the original page and its text, removes metadata, then re-reads the output to confirm no text remains under any box.

Checked 2026-10-05. The diagnostic above runs in this tab; your file is not uploaded.