PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchiTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
A black box over PDF text may hide it from view without removing it from the file. In one court-documented example, readers could recover text beneath black bars by copying and pasting; other failures have exposed document history or leaked clues through text positioning. These are different risks, and a visually clean page alone does not prove a PDF is safely redacted.
What the three failures show
PDF redaction can fail at more than one layer. A cover-up may leave the original text object intact; document properties or revision remnants may expose information outside the visible page; and even after text is removed, character-position data may reveal clues. Each mechanism calls for a different check.
Failure 1: Black bars covered text that was still there
The U.S. District Court for the Eastern District of Tennessee recounts a November 2010 court-opinion PDF in which black bars covered grand-jury-related passages, but the text itself was not erased. Copying and pasting from beneath the bars made the text readable. The guide also cites an earlier 2006 baseball-steroids leak case and a Justice Department document about an internal survey as examples of the same broad mistake; it does not provide full case records for those incidents. Read the Tennessee court’s PDF-redaction guidance.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
The underlying problem is the difference between appearance and content. A black rectangle, highlight, or white font can change what a page displays while leaving text available to select, search, or copy. If the original text object remains, the cover is not a redaction.
#1 Best Overall
![Corel WordPerfect Office Standard 2021 | Office Suite of Word Processor, Spreadsheets & Presentation Software [PC Download]](https://m.media-amazon.com/images/I/41Tj94MBfQL._SL160_.jpg)
- A complete office suite for word processing, spreadsheets, presentations, note taking, eBook publishing, and more
- Easily open, edit, and share files with extensive support for 60 formats, including Microsoft Word, Excel, and PowerPoint
- Includes the Oxford Concise Dictionary, which contains tens of thousands of definitions, phrases, phonetic spellings, scientific and specialist words
- Create fillable PDF forms with a range of form controls, including text fields, check boxes, drop-down lists, and more
- 900 TrueType fonts, 10,000 clipart images, 300 templates, and 175 digital photos
Failure 2: Hidden document history survived the visible edit
A PDF can carry information beyond what appears on the page. The U.S. District Court for the District of New Jersey identifies author names, file-server locations, full-size versions of cropped images, and earlier text revisions as examples of hidden data. It warns that black overlays and white text do not protect what lies underneath, and that deleted text or prior revisions may be exposed by manipulating the file. See the New Jersey court’s guidance on redacting with Acrobat.
This is a separate issue from a visible black bar that leaves text selectable: removing the page’s visible material does not necessarily remove document properties, embedded image content, or revision history. A reviewer should consider what else the file retains, not just whether the page looks right.
Rank #2
Failure 3: Text removal did not eliminate every leak
A 2022 study, Story Beyond the Eye: Glyph Positions Break PDF Text Redaction, examined 11 popular PDF redaction tools. The authors found that two left selected text beneath redactions. They also reported leakage from other tools, including cases where text was removed but character positions and other information could still reveal clues. The researchers recovered information from hundreds of real-world redactions, including material in OIG reports and FOIA responses. Read the 2022 study.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteThe result is not a current product ranking: the study describes the tools and versions it examined, not necessarily today’s releases. Its broader lesson is that excising the text object addresses one failure mode but does not, by itself, prove every inference channel has been closed.
Rank #3
- Save money by using PDF Fusion to view over 100 file formats without having to purchase additional software
- Merge incompatible files quickly and easily by dragging and dropping in PDF Fusion to create a new PDF documents
- Save time with PDF Fusion's editing tools to reuse the content from existing documents without starting from scratch
How common were failures in one published corpus?
A separate study examined 39,664 PDFs published by 75 security agencies across 47 countries. In the files the researchers classified as sanitized, 65% still contained sensitive information; seven agencies had sanitized some files. These are results for that study’s 2021 corpus and method, not an estimate of all PDFs or current practice. The study publication page describes the research.
How to redact and verify a PDF
- Remove information at the source when possible. The New Jersey court recommends omitting the information from the original document and saving the redacted version under a new name. The Tennessee court similarly advises editing the original word-processing document to remove—not cover up—the text, then publishing a new PDF. New Jersey guidance and Tennessee guidance.
- If editing the PDF directly, use a real redaction operation. Do not substitute a drawing, annotation, highlight, or white text. The Australian court’s guidance describes Acrobat Professional’s redaction tool as permanently replacing redacted text and notes an option to remove metadata. Product behavior and menus can change, so consult instructions for the version installed. Read the Federal Court of Australia’s redaction guidance.
- Check the exported file, not just the editing view. Search for the sensitive string and try selecting and copying where it was removed. The Australian court describes copy-and-paste and search checks for its word-processing roundtrip method. Also review document properties and consider whether revisions or embedded content could retain information, as the New Jersey court warns.
- Keep the source and the shareable copy separate. If an unredacted original must be retained, store it with appropriate access controls and share only the verified redacted output. Filing, retention, and disclosure requirements vary by jurisdiction; follow the current rules that apply to the document.
What a verification check can and cannot establish
Searching and copying the final PDF can catch a common failure: text that remains underneath a visual cover. Reviewing properties and revision-related content can help identify other remnants. These checks are useful, but the 2022 study shows why successful text removal should not be treated as proof that all possible leakage has been eliminated. For sensitive material, use a workflow that actually removes content, follow applicable court or organizational rules, and have the output independently reviewed when the consequences of disclosure are high.
Quick Recap
Rank #4
![Corel WordPerfect Office Standard Upgrade 2021 | Office Suite of Word Processor, Spreadsheets & Presentation Software [PC Download]](https://m.media-amazon.com/images/I/41lK-6MiKeL._SL160_.jpg)
- A complete office suite for word processing, spreadsheets, presentations, note taking, eBook publishing, and more
- Easily open, edit, and share files with extensive support for 60+ formats, including Microsoft Word, Excel, and PowerPoint
- The Oxford Concise Dictionary now comes standard with WordPerfect, containing tens of thousands of definitions, phrases, phonetic spellings, scientific and specialist words
- Create fillable PDF forms with a range of form controls, including text fields, check boxes, drop-down lists, and more
- 900+ TrueType fonts, 10,000+ clipart images, 300+ templates, and 175+ digital photos
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
