How to Watermark a PDF (and Get Arabic Text Right)
Add a text watermark to a PDF for free, including a real technical look at why Arabic watermark text is harder to get right than English.
Watermarking a PDF sounds simple — stamp some text across the page — until you try it with Arabic text and the watermark comes out as boxes, disconnected letters, or missing entirely. Here's how to watermark a PDF properly, and what's actually happening under the hood with Arabic text specifically.
Add a text watermark
Open Watermark PDF, type your text (a name, "CONFIDENTIAL", a company name), and choose its position, rotation, opacity and size. The watermark is drawn into every page of the document, not just displayed as an overlay — it's part of the saved file.
Why Arabic watermark text is a harder problem
Most PDF tools embed a small, fixed font — usually a Latin one — into the file. Arabic text needs a font that actually contains Arabic glyphs, and Arabic script also needs shaping (the same letter looks different at the start, middle or end of a word) and right-to-left layout, none of which a Latin-only font can do. That's why so many free watermark tools silently produce garbled Arabic or fall back to boxes.
How Convorae handles this
For Arabic watermark text, a proper Arabic font (Noto Sans Arabic) is fetched and embedded into the PDF along with your text — resolved so only the glyphs your specific text actually uses are included, keeping the file small. This is real, tested handling, not a guess: it was built and verified specifically because generic PDF libraries don't do this correctly out of the box.
Pick opacity and position deliberately
A watermark meant to deter copying (like "CONFIDENTIAL") usually works best diagonal, low-opacity, and centered so it can't be easily cropped out. A watermark meant to be read (like a company name in a footer) should be higher-opacity and positioned where it won't overlap body text.
Watermark the final file, not the parts
If a document is assembled from pieces — merged chapters, an extracted appendix — watermark once at the very end, on the final combined PDF. One pass stamps every page evenly with the same opacity and position. Watermarking each part before merging works too, but any page you later extract, add or replace will be missing the stamp, and parts watermarked at different times often end up with subtly different settings.
What a watermark can and cannot protect
A watermark is a visible claim, not a lock. It deters casual copying, makes ownership obvious in screenshots and printouts, and survives ordinary sharing because it is baked into every page. It does not encrypt the document, and someone determined, with a PDF editor, can attempt to remove or cover drawn content. For genuinely sensitive files, a watermark is one layer — combine it with sensible sharing (send only the pages people need) rather than treating the stamp as security.
Screen versus print
Opacity behaves differently on paper. A diagonal watermark that looks faint on a bright screen can print darker and more distracting, while a very light stamp can nearly vanish on a cheap printer. If the document is headed for print, print one test page first and judge the balance there — the goal is a mark that is clearly present without fighting the text for attention.
Quick tips
- Test with your actual Arabic text before finalizing — mixed Arabic/English watermarks (a name plus a date) are supported.
- Lower opacity (10-20%) keeps a watermark visible without making the underlying text hard to read.
- The watermark is baked into the file itself — recipients can't toggle it off, but a determined person could still crop or edit it out; a watermark deters casual copying, it isn't DRM.
- Watermark after merging and editing are finished — one pass over the final file, with even coverage on every page.
- Printing the document? Print one test page: watermark strength on paper rarely matches the screen.